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Comparison of kinetic theory models of laser ablation of carbon
The paper compares the predictions of three-dimensional kinetic theory models of laser ablation of carbon. All the models are based on the moment solution of the Boltzmann equation for arbitrary strong evaporation but use different approximations. Comparison of the model predictions demonstrated that the choice of the particular model has very little influence on the results. The influence of the heat conduction from the gas to the solid phase was also found to be negligible in this problem.
Shusser, Michael [Faculty of Mechanical Engineering, Technion, Haifa 32000 (Israel)
Laser Ablation: Fundamentals and Applications
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90 This seminar will include both experimental and theoretical topics of ultrafast laser ablation. In the first part, fundamental physics of ultrafast laser-material...
Multiple target laser ablation system
A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.
Mashburn, Douglas N. (Knoxville, TN)
Laser ablation based fuel ignition
There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.
Early, J.W.; Lester, C.S.
New Combined Laser Ablation Platform Determines Cell Wall Chemistry...
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ablation laser mass spectrometer molecular beam REMPI laser NREL has designed and developed a combined laser ablation pulsed sample introductionmass spectrometry platform that...
Laser Ablation Technology for Chemical Analysis : Technologies...
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of gray dots transitioning to a line art drawing of a cityscape and residential houses. Laser Ablation Technology for Chemical Analysis Analyzing materials to determine their...
A study of particle generation during laser ablation with applications
ferntosecond laser ablation of brass: Particulate and ICPMSfrom laser ablation of brass 5.1 Influence of particleablated particles from brass alloy yielded the relation
Liu, Chunyi
Laser Ablation - From Picoseconds to Microseconds
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Laser Ablation - From Picoseconds to Microseconds Speaker(s): Xianglei Mao Date: October 20, 2000 - 12:00pm Location: Bldg. 90 Seminar HostPoint of Contact: Julie Osborn Laser...
Ablative Laser Propulsion: An Update, Part I
Science Conference Proceedings (OSTI)
This paper presents an updated review of studies on Ablative Laser Propulsion conducted by the Laser Propulsion Group (LPG) at the University of Alabama in Huntsville. In particular, we describe the newest results of our experimental study of specific impulses and coupling coefficients achieved by double-pulsed ablation of graphite, aluminum, copper and lead targets.
Pakhomov, Andrew V.; Cohen, Timothy; Lin Jun; Thompson, M. Shane; Herren, Kenneth A. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Information Systems Laboratories, Inc., Brownsboro, Alabama, 35741 (United States); National Space Science and Technology Center, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)
Ablative Laser Propulsion: An Update, Part II
Science Conference Proceedings (OSTI)
This paper presents an updated review of studies on Ablative Laser Propulsion conducted by the Laser Propulsion Group (LPG) at the University of Alabama in Huntsville. In particular, we describe the experimental technique developed for determination of specific impulses from plasma plume imaging with an intensified CCD camera.
Pakhomov, Andrew V.; Lin Jun; Thompson, M. Shane [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Information Systems Laboratories, Inc., Brownsboro, Alabama, 35741 (United States)
Laser ablated hard coating for microtools
Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10-20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode.
McLean, II, William (Oakland, CA); Balooch, Mehdi (Berkeley, CA); Siekhaus, Wigbert J. (Berkeley, CA)
A Review of Laser Ablation Propulsion
Laser Ablation Propulsion is a broad field with a wide range of applications. We review the 30-year history of laser ablation propulsion from the transition from earlier pure photon propulsion concepts of Oberth and Saenger through Kantrowitz's original laser ablation propulsion idea to the development of air-breathing 'Lightcraft' and advanced spacecraft propulsion engines. The polymers POM and GAP have played an important role in experiments and liquid ablation fuels show great promise. Some applications use a laser system which is distant from the propelled object, for example, on another spacecraft, the Earth or a planet. Others use a laser that is part of the spacecraft propulsion system on the spacecraft. Propulsion is produced when an intense laser beam strikes a condensed matter surface and produces a vapor or plasma jet. The advantages of this idea are that exhaust velocity of the propulsion engine covers a broader range than is available from chemistry, that it can be varied to meet the instantaneous demands of the particular mission, and that practical realizations give lower mass and greater simplicity for a payload delivery system. We review the underlying theory, buttressed by extensive experimental data. The primary problem in laser space propulsion theory has been the absence of a way to predict thrust and specific impulse over the transition from the vapor to the plasma regimes. We briefly discuss a method for combining two new vapor regime treatments with plasma regime theory, giving a smooth transition from one regime to the other. We conclude with a section on future directions.
Phipps, Claude [Photonic Associates, LLC, 200A Ojo de la Vaca Road, Santa Fe NM 87508 (United States); Bohn, Willy [Bohn Laser Consult, Weinberg Weg 43, Stuttgart (Germany); Lippert, Thomas [Paul Scherrer Institut, CH5232 Villigen PSI (Switzerland); Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Chikusa-ku, Nagoya (Japan); Schall, Wolfgang [DLR Institute of Technical Physics, Stuttgart (Germany); Sinko, John [Micro-Nano GCOE, Nagoya University, Furo-cho, Nagoya, Aichi (Japan)
Numerical simulation of copper ablation by ultrashort laser pulses
Using a modified self-consistent one-dimensional hydrodynamic lagrangian fluid code, laser ablation of solid copper by ultrashort laser pulses in vacuum was simulated to study fundamental mechanisms and to provide a guide for drilling periodic microholes or microgratings on the metal surface. The simulated laser ablation threshold is a approximate constancy in femtosecond regime and increases as the square root of pulse duration in picosecond regime. The ablation depth as a function of pulse duration shows four different regimes and a minimum for a pulse duration of ~ 12ps for various laser fluences. The influence of laser-induced plasma shielding on ablation depth is also studied.
Ding, PengJi; Li, YuHong
Solar cell contact formation using laser ablation
The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.
Harley, Gabriel; Smith, David; Cousins, Peter
Spectroscopic characterization of laser ablation brass plasma
Science Conference Proceedings (OSTI)
We present optical emission studies of the laser ablation brass plasma generated by the fundamental, second, and third harmonics of a neodymium doped yttrium aluminum garnet laser. The spectra predominantly reveal the spectral lines of the neutral and singly ionized copper and zinc. The excitation temperatures are determined by the Boltzmann plot method, whereas the electron number densities have been extracted from the Stark broadened line profiles. The spatial variations in the spectral line intensities and the plasma parameters at 1000, 500, and 100 mbar air pressures have been evaluated. Besides, the effect of the ambient gases (He, Ne, and Ar), the laser irradiance, and the laser wavelengths on the plasma parameters have been investigated.
Shaikh, Nek M. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Institute of Physics, University of Sindh, 76080 Jamshoro (Pakistan); Hafeez, Sarwat; Kalyar, M. A.; Ali, R.; Baig, M. A. [Atomic and Molecular Physics Laboratory, Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)
UV laser ablation of parylene films from gold substrates
Parylene films, coating gold substrates, were removed by laser ablation using 248 nm light from an excimer laser. Each sample was processed by a different number of pulses in one of three different environments: air at atmospheric pressure, nitrogen at atmospheric pressure, and vacuum. The laser-induced craters were analyzed by optical microscopy and x-ray photoelectron spectroscopy. Multi-pulse ablation thresholds of gold and parylene were estimated.
O. R. Musaev, P. Scott, J. M. Wrobel, and M. B. Kruger
Nanosecond and femtosecond laser ablation of brass: Particulate and ICPMS measurements
Femtosecond Laser Ablation of Brass: Particulate and ICPMScompared for ablating brass alloys. All operating parametersby resolidi- fication of molten brass. Melting and splashing
Liu, C.; Mao, X.L.; Mao, S.; Zeng, X.; Greif, R.; Russo, R.E.
Laser ablation for the synthesis of carbon nanotubes
Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.
Holloway, Brian C; Eklund, Peter C; Smith, Michael W; Jordan, Kevin C; Shinn, Michelle
Laser ablation of nanoscale particles with 193 nm light
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Laser ablation of nanoscale particles with 193 nm light Laser ablation of nanoscale particles with 193 nm light Title Laser ablation of nanoscale particles with 193 nm light Publication Type Journal Article Year of Publication 2007 Authors Choi, Jong Hyun, Donald Lucas, and Catherine P. Koshland Journal Journal of Physics: Conference Series Volume 59 Start Page 54 Issue 1 Pagination 54-59 Abstract Laser interaction with nanoscale particles is distinct and different from laser-bulk material interaction, where a hot plasma is normally created. Here, we review our studies on 193 nm laser ablation of various nanoscale particles including NaCl, soot, polystyrene, and gold. The 20 ns laser beam with fluences up to 0.3 J/cm2 irradiates nanoparticles in a gas stream at laser repetition rates from 10 to 100 Hz. The particle size distributions before and after irradiation are measured with a scanning mobility particle sizer (SMPS), and particle morphology is examined with electron microscopy. All the nanomaterials studied exhibit a similar disintegration pattern and similar particle formation characteristics. No broadband emission associated with particle heating or optical breakdown is observed. The nanoparticles formed after irradiation have a smaller mean diameter and an order of magnitude higher number concentration with a more spherical shape compared to the original particles. We use the photon-atom ratio (PAR) to interpret the laser-particle interaction energetics.
Science Conference Proceedings (OSTI)
This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining {lambda}{sub o}; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.
Lindley, R.A. [Michigan Univ., Ann Arbor, MI (United States)
Optical far-and near-field femtosecond laser ablation of Si for...
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Optical far-and near-field femtosecond laser ablation of Si for nanoscale chemical analysis Title Optical far-and near-field femtosecond laser ablation of Si for nanoscale chemical...
Ultrafast laser ablation of gold thin film targets
Science Conference Proceedings (OSTI)
Ultrafast laser ablation of a gold thin film is studied and compared with that of a bulk target, with particular emphasis given to the process of nanoparticles generation. The process is carried out in a condition where a single laser shot removes all the irradiated film spot. The experimental results evidence interesting differences and, in particular, a reduction of the nanoparticles size, and a narrowing of a factor two of their size distribution in the case of ablation of a thin film target, a feature which we relate to a more uniform heating of the target material. We thus show that ultrashort laser ablation of thin films provides a promising way of controlling plume features and nanoparticles size.
Amoruso, S.; Ausanio, G.; Bruzzese, R. [Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Nedyalkov, N. N.; Atanasov, P. A. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Boulevard, Sofia 1784 (Bulgaria); Wang, X. [CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)
Generation of Core/shell Nanoparticles with Laser Ablation
Two types of core/shell nanoparticles (CS-NPs) generation based on laser ablation are developed in this study, namely, double pulse laser ablation and laser ablation in colloidal solutions. In addition to the study of the generation mechanism of CS-NPs in each scheme, the optical properties of designed CS-NPs are determined with UV-VIS-NIR spectroscopy and EM field simulation. In the first scheme, which is double pulse laser ablation, two laser beams are fired in a sequence on two adjacent targets with different material. We have successfully demonstrated the generation of Sn/Glass, Zn/Glass, Zn/Si, Ge/Si, and Cu/Zn CS-NPs. Key factors affecting the generation of CS-NPs are (1) surface tensions of the constructing materials affecting the associated Gibbs free energy of CS-NPs, (2) physical properties of selected background gases (i.e., He and Ar), (3) delay time between two laser pulses, and (4) the amount of laser energy. The second scheme examined for the generation of CS-NPs is through laser ablation of solid targets in colloidal solutions. Compared to the double pulse laser ablation, this second approach provides better control of the size and shape of the resulting CS-NPs. Two colloidal solutions, namely, Au and SiO2 colloidal solution are applied in the second scheme. Key factors affecting the formation of CS-NPs with the second scheme and are (a) the adhesion energy between the shell and the core material, (b) the diameter of the core and (c) the laser ablation time and the laser energy. Red shift of absorption peaks are measured in both SiO2/Au and SiO2/Ag colloids compared with pure nanoparticles (NPs). The amount of red-shift is very sensitive to the shell thickness of the CS-NPs. The same red shift is reproduced with the corresponding full wave analysis. The observed red shift can be attributed to the additional surface plasmon resonance at the interface of metal/dielectric of the CS-NPs compared with pure nanoparticles. Through adjusting the material and size combination, the absorption peak of the CS-NPs can be tuned in a limit range around the intrinsic absorption peak of the metal of the CS-NPs. The freedom of adjusting the absorption peak makes CS-NPs is favorable in bio and optical applications.
Jo, Young Kyong
CO{sub 2} Laser Ablation Propulsion Tractor Beams
Manipulation of objects at a distance has already been achieved with no small measure of success in the realm of microscopic objects on the scale size of nanometers to micrometers in applications including laser trapping and laser tweezers. However, there has been relatively little effort to apply such remote control to macroscopic systems. A space tractor beam could be applied to a wide range of applications, including removal of orbital debris, facilitation of spacecraft docking, adjustment of satellite attitude or orbital position, etc. In this paper, an ablative laser propulsion tractor beam is demonstrated based on radiation from a CO{sub 2} laser. Cooperative, layered polymer targets were used for remote impulse generation using a CO{sub 2} laser. The use of a structured ablatant enabling switching between thrust directional parity (i.e., forward or reverse) and imparting torque to a remote target. Fluence-dependent results are presented in the context of polymer ablation modeling work and with consideration of confined ablation effects.
Sinko, John E. [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Schlecht, Clifford A. [Institute for Materials and Complexity, Saint Louis, MO 63112 (United States)
Cluster Generation Under Pulsed Laser Ablation Of Compound Semiconductors
A comparative experimental study of pulsed laser ablation in vacuum of two binary semiconductors, zinc oxide and indium phosphide, has been performed using IR- and visible laser pulses with particular attention to cluster generation. Neutral and cationic Zn{sub n}O{sub m} and In{sub n}P{sub m} particles of various stoichiometry have been produced and investigated by time-of-flight mass spectrometry. At ZnO ablation, large cationic (n>9) and all neutral clusters are mainly stoichiometric in the ablation plume. In contrast, indium phosphide clusters are strongly indium-rich with In{sub 4}P being a magic cluster. Analysis of the plume composition upon laser exposure has revealed congruent vaporization of ZnO and a disproportionate loss of phosphorus by the irradiated InP surface. Plume expansion conditions under ZnO ablation are shown to be favorable for stoichiometric cluster formation. A delayed vaporization of phosphorus under InP ablation has been observed that results in generation of off-stoichiometric clusters.
Bulgakov, Alexander V.; Evtushenko, Anton B.; Shukhov, Yuri G. [Institute of Thermophysics SB RAS, Lavrentyev Ave. 1, 630090 Novosibirsk (Russian Federation); Ozerov, Igor; Marine, Wladimir [Universite de la Mediterranee, CINaM, UPR CNRS 3118, 13288 Marseille (France)
Laser induced modification and ablation of InAs nanowires
InAs nanowires were irradiated locally under an ambient condition using a focused laser beam, which led to laser ablation and thinning of the nanowires. We show that the laser beam can induce a reduction of the local As concentration in an InAs nanowire; the change leads to a significant decrease of local melting temperature of InAs, which results in the thinning and eventually breaking of the nanowire. The results indicate that chemical and mechanical modifications of an InAs nanowire can be accomplished by using a confocal laser beam, which may prove to be a convenient approach in fabricating nanostructural materials and nanodevices.
He Jiayu; Chen Pingping; Lu Wei; Dai Ning [Shanghai Institute of Technical Physics, Academy Science of China, Shanghai (China); Zhu Daming [Department of Physics, University of Missouri - Kansas City, Kansas City, Missouri 64110 (United States)
Solid material evaporation into an ECR source by laser ablation
Science Conference Proceedings (OSTI)
In an effort to explore new methods of producing ion beams from solid materials, we are attempting to develop a laser-ablation technique for evaporating materials directly into an ECR ion source plasma. A pulsed NdYaG laser with approximately 25 watts average power and peak power density on the order of 10{sup 7} W/cm{sup 2} has been used off-line to measure ablation rates of various materials as a function of peak laser power. The benefits anticipated from the successful demonstration of this technique include the ability to use very small quantities of materials efficiently, improved material efficiency of incorporation into the ECR plasma, and decoupling of the material evaporation process from the ECR source tuning operation. Here we report on the results of these tests and describe the design for incorporating such a system directly with the ATLAS PII-ECR ion source.
Harkewicz, R.; Stacy, J.; Greene, J.; Pardo, R.C.
The field of the invention is atmospheric pressure mass spectrometry (MS), and more specifically a process and apparatus which combine infrared laser ablation (LA) with electrospray ionization (ESI).
Vertes, Akos (Reston, VA); Nemes, Peter (Silver Spring, MD)
The field of the invention is atmospheric pressure mass spectrometry (MS), and more specifically a process and apparatus which combine infrared laser ablation with electrospray ionization (ESI).
Vertes, Akos; Nemes, Peter
The field of the invention is atmospheric pressure mass spectrometry (MS), and more specifically a process and apparatus which combine infrared laser ablation with electrospray ionization (ESI).
Vertes, Akos; Nemes, Peter
The field of the invention is atmospheric pressure mass spectrometry (MS), and more specifically a process and apparatus which combine infrared laser ablation with electrospray ionization (ESI).
Vertes, Akos; Nemes, Peter
Testing of concrete by laser ablation
A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.
Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.
Testing of concrete by laser ablation
A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.
Flesher, Dann J. (Benton City, WA); Becker, David L. (Kennewick, WA); Beem, William L. (Kennewick, WA); Berry, Tommy C. (Kennewick, WA); Cannon, N. Scott (Kennewick, WA)
Laser ablative synthesis of carbon nanotubes
An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.
Smith, Michael W. (Newport News, VA); Jordan, Kevin (Newport News, VA); Park, Cheol (Yorktown, VA)
Nanosecond and femtosecond laser ablation of brass: Particulate and ICPMS measurements
Science Conference Proceedings (OSTI)
Femtosecond and nanosecond lasers were compared for ablating brass alloys. All operating parameters from both lasers were equal except for the pulse duration. The ablated aerosol vapor was collected on silicon substrates for particle size measurements or sent into an inductively coupled plasma mass spectrometer. The diameters and size distribution of particulates were measured from scanning electron microscope (SEM) images of the collected ablated aerosol. SEM measurements showed that particles ablated using nanosecond pulses were single spherical entities ranging in diameter from several micrometers to several hundred nanometers. Primary particles ablated using femtosecond ablation were {approx}100 nm in diameter but formed large agglomerates. ICPMS showed enhanced signal intensity and stability using femtosecond compared to nanosecond laser ablation.
Liu, C.; Mao, X.L.; Mao, S.; Zeng, X.; Greif, R.; Russo, R.E.
Peak polarity overturn for charged particles in laser ablation process
Science Conference Proceedings (OSTI)
The charged particles emitted during laser ablation off a brass target are detected using a metal probe in air. A special phenomenon is found in the recorded signals: following a giant electromagnetic peak observed immediately after the emission of the pulsed laser, a minor peak occurs whose polarity merely depends on the distance between the probe and the laser focal spot on the target. Under the condition of our experiment, the overturn point is 1.47 mm, i.e., the minor peak remains negative when the probe distance is less than 1.47 mm; it becomes positive while the probe is set at a distance beyond 1.47 mm. A hypothesis is proposed to explain the overturn that takes the flight behavior of the charged particles both in plasma and propagating shock wave into consideration.
Zhang, P.; Ji, Y. J.; Lai, X. M.; Bian, B. M.; Li, Z. H. [Department of Information Physics and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)
Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume.
Geohegan, D.B.
Science Conference Proceedings (OSTI)
By combining structural and chemical thin film analysis with detailed plume diagnostics and modeling of the laser plume dynamics, we are able to elucidate the different physical mechanisms determining the stoichiometry of the complex oxides model material SrTiO{sub 3} during pulsed laser deposition. Deviations between thin film and target stoichiometry are basically a result of two effects, namely, incongruent ablation and preferential scattering of lighter ablated species during their motion towards the substrate in the O{sub 2} background gas. On the one hand, a progressive preferential ablation of the Ti species with increasing laser fluence leads to a regime of Ti-rich thin film growth at larger fluences. On the other hand, in the low laser fluence regime, a more effective scattering of the lighter Ti plume species results in Sr rich films.
Wicklein, S.; Koehl, A.; Dittmann, R. [Peter Gruenberg Institut and JARA-FIT, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Sambri, A.; Amoruso, S.; Wang, X.; Bruzzese, R. [CNR-SPIN and Dipartimento di Scienze Fisiche, Complesso Universitario di Monte Sant'Angelo, Via Cintia, I-80125 Napoli (Italy)
Time Resolved Shadowgraph Images of Silicon during Laser Ablation:Shockwaves and Particle Generation
Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume.
Liu, C.Y.; Mao, X.L.; Greif, R.; Russo, R.E.
The direct measurement of ablation pressure driven by 351-nm laser radiation
Science Conference Proceedings (OSTI)
The instantaneous scaling of ablation pressure to laser intensity is directly inferred for ramp compression of diamond targets irradiated by 351-nm light. Continuously increasing pressure profiles from 100 to 970 GPa are produced by direct-drive laser ablation at intensities up to 7 x 10{sup 13} W/cm{sup 2}. The free-surface velocity on the rear of the target is used to directly infer the instantaneous ablation-pressure profile at the front of the target. The laser intensity on target is determined by laser power measurements and fully characterized laser spots. The ablation pressure is found to depend on the laser intensity as P(GPa)=42({+-}3)[I(TW/cm{sup 2})]{sup 0.71({+-}0.01)}.
Fratanduono, D. E. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Boehly, T. R. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Celliers, P. M.; Eggert, J. H.; Smith, R. F.; Hicks, D. G.; Collins, G. W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Barrios, M. A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and Astronomy, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and Astronomy, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)
Ablation driven by hot electrons generated during the ignitor laser pulse in shock ignition
An analytical model for the ablation driven by hot electrons is presented. The hot electrons are assumed to be generated during the high intensity laser spike used to produce the ignitor shock wave in the shock ignition driven inertial fusion concept, and to carry on the absorbed laser energy in its totality. Efficient energy coupling requires to keep the critical surface sufficiently close to the ablation front and this goal can be achieved for high laser intensities provided that the laser wavelength is short enough. Scaling laws for the ablation pressure and the other relevant magnitudes of the ablation cloud are found in terms of the laser and target parameters. The effect of the preformed plasma assembled by the compression pulse, previous to the ignitor, is also discussed. It is found that a minimum ratio between the compression and the ignitor pulses would be necessary for the adequate matching of the corresponding scale lengths.
Piriz, A. R.; Rodriguez Prieto, G. [E.T.S.I. Industriales, Universidad de Castilla-La Mancha and Instituto de Investigaciones Energeticas, 13071 Ciudad Real (Spain); Tahir, N. A. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Zhang, Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, 116024 Dalian (China); Liu, S. D.; Zhao, Y. T. [Institute of Modern Physics, Chinese Academy of Science, 730000 Lanzhou (China)
CO{sub 2} Laser Ablation Area Scaling And Redeposition On Flat Polyoxymethylene Targets
One of the remaining unknown subjects of laser propulsion involves whether special benefits or challenges exist for applying laser ablation propulsion to targets with particularly large or small spot areas. This subject is of high importance for a wide range of topics ranging from laser removal of space debris to micropropulsion for laser propulsion vehicles. Analysis is complex since different ablation phenomena are dominant between atmosphere and vacuum conditions. Progress has also been impeded by the difficulty of setting control parameters (particularly fluence) constant while the spot area is adjusted. It is also usually difficult for one group to address small- and large-area effects using a single high-power laser system. Recent collaborative experiments on laser ablation area scaling at several institutions, using 100-J class and 10-J class CO{sub 2} lasers, have advanced the understanding of laser propulsion area scaling. The spot area-dependence of laser propulsion parameters has been investigated over an area range covering approximately 0.05-50 cm{sup 2} at low fluence of about 0.6 J/cm{sup 2}. The experiments were conducted well below the threshold for plasma formation, and provide an estimate of the ablation threshold for CO{sub 2} laser ablation of POM.
Sinko, John E. [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan 464-8603 (Japan); Scharring, Stefan; Eckel, Hans-Albert [German Aerospace Center (DLR)-Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart (Germany); Tsukiyama, Yosuke; Umehara, Noritsugu [Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan 464-8603 (Japan); Ichihashi, Katsuhiro; Ogita, Naoya; Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan 464-8603 (Japan); Roeser, Hans-Peter [Institute of Space Systems (IRS), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)
Formation of periodic structures upon laser ablation of metal targets in liquids
Experimental data on the formation of ordered microstructures produced upon ablation of metal targets in liquids irradiated by a copper vapour laser or a pulsed Nd:YAG laser are presented. The structures were obtained on brass, bronze, copper, and tungsten substrates immersed in distilled water or ethanol. As a result of multiple-pulse laser ablation by a scanning beam, ordered microcones with pointed vertexes are formed on the target surface. The structures are separated by deep narrow channels. The structure period was experimentally shown to increase linearly with diameter of the laser spot on the target surface. (interaction of laser radiation with matter)
Kazakevich, Pavel V; Simakin, Aleksandr V; Shafeev, Georgii A [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Bioavailable nanoparticles obtained in laser ablation of a selenium target in water
Science Conference Proceedings (OSTI)
The process of producing colloidal solutions of selenium nanoparticles in water using the laser ablation method is described. The prospects of using nanoparticles of elementary selenium as a nutrition source of this microelement are discussed. (nanoparticles)
Kuzmin, P G; Shafeev, Georgii A; Voronov, Valerii V; Raspopov, R V; Arianova, E A; Trushina, E N; Gmoshinskii, I V; Khotimchenko, S A
Laser Ablation of Organic Materials for discrimination of bacteria in an
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Laser Ablation of Organic Materials for discrimination of bacteria in an Laser Ablation of Organic Materials for discrimination of bacteria in an organic background Title Laser Ablation of Organic Materials for discrimination of bacteria in an organic background Publication Type Conference Proceedings Year of Publication 2009 Authors Baudelet, Matthieu, Myriam Boueri, Jin Yu, Xianglei Mao, Samuel S. Mao, and Richard E. Russo Conference Name Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIII Series Title Proceedings SPIE Volume 7214 Pagination 72140J Date Published 02/2009 Abstract We demonstrate in this paper that laser ablation allows efficient analysis of organic and biological materials. Such analysis is based on laser-induced breakdown spectroscopy (LIBS) which consists in the detection of the optical emission from the plasma induced by a high intensity laser pulse focused on the sample surface. The optimization of the ablation regime in terms of laser parameters (pulse duration, wavelength, fluence) is important to generate a plasma suitable for the analysis. We first present the results of a study of laser ablation of organic samples with different laser parameters using time-resolved shadowgraph. We correlate the early stage expansion of the plasma to its optical emission properties, which allows us to choose suitable laser parameters for an efficient analysis of organic or biological samples by LIBS. As an illustration of the analytical ability of LIBS for biological materials, we show that the emission from CN molecules can be used to distinguish between biological and inorganic samples. Native CN molecular fragment directly ablated from a biological sample are identified using time-resolved LIBS. Those due to recombination with nitrogen contained in atmospheric air can be distinguished with their specific time evolution behavior.
Compact And Robust Laser Impulse Measurement Device, With Ultrashort Pulse Laser Ablation Results
An impulse measurement device and analysis package was conceived, designed, constructed, tested, and demonstrated to be capable of: measuring nanoNewton-seconds to milliNewton-seconds of impulse due to laser-ablation; being transported as carry-on baggage; set-up and tear-down times of less than an hour; target exchange times of less than two minutes (targets can be ablated at multiple positions for thousands of shots); measurements in air and in vacuum; error of just a few percent; repeatability over a wide range of potential systematic error sources; and time between measurements, including ring-down and analysis, of less than 30 seconds. The instrument consists of a cantilever (i.e. leaf spring), whose time-dependent displacement/oscillation is measured and analyzed to determine the impulse imparted by a laser pulse to a target. These shapes are readily/commercially available, and any target material can be used, provided it can be fashioned in the form of a cantilever, or as a coating/film/tape, suitable for mounting on a cantilever of known geometry. The instrument was calibrated both statically and dynamically, and measurements were performed on brass, steel, and Aluminum, using laser pulses of {approx}7 ns, {approx}500 ps, and {approx}500 fs. The results agree well with those published in the literature, with surface effects, atmosphere, and pre-/post-pulses demonstrating interesting effects and indicating areas for further study. These parameters should be carefully controlled and held constant during a series of measurements. The impulse imparted by ablation due to laser filaments in air was also explored.
Kremeyer, Kevin; Lapeyre, John; Hamann, Steven [Physics, Materials, and Applied Mathematics Research, L.L.C. PM and AM Research in Collaboration with AFRL 1665 E. 18th Street, Suite 112 Tucson, AZ, 85719 (United States)
Toward laser ablation Accelerator Mass Spectrometry of actinides
Science Conference Proceedings (OSTI)
A project to measure neutron capture cross sections of a number of actinides in a reactor environment by Accelerator Mass Spectrometry (AMS) at the ATLAS facility of Argonne National Laboratory is underway. This project will require the precise and accurate measurement of produced actinide isotopes in many (>30) samples irradiated in the Advanced Test Reactor at Idaho National Laboratory with neutron fluxes having different energy distributions. The AMS technique at ATLAS is based on production of highlycharged positive ions in an electron cyclotron resonance (ECR) ion source followed by acceleration in the ATLAS linac and mass-to-charge (m/q) measurement at the focus of the Fragment Mass Analyzer. Laser ablation was selected as the method of feeding the actinide material into the ion source because we expect it will have higher efficiency and lower chamber contamination than either the oven or sputtering techniques, because of a much narrower angular distribution of emitted material. In addition, a new multi-sample holder/changer to allow quick change between samples and a computer-controlled routine allowing fast tuning of the accelerator for different beams, are being developed. An initial test run studying backgrounds, detector response, and accelerator scaling repeatability was conducted in December 2010. The project design, schedule, and results of the initial test run to study backgrounds are discussed.
R. C. Pardo; F. G. Kondev; S. Kondrashev; C. Nair; T. Palchan; R. Scott; D. Seweryniak; R. Vondrasek; M. Paul; P. Collon; C. Deibel; M. Salvatores; G. Palmiotti; J. Berg; J. Fonnesbeck; G. Imel
Control of electroosmotic flow in laser-ablated and chemically ...
Science Conference Proceedings (OSTI)
... Chemical modification of hydro- lyzed and ablated PETG channels to produce ... carbon tape and coated with approximately 10 nm car- bon before ...
Pulsed laser ablation of binary semiconductors: mechanisms of vaporisation and cluster formation
Formation of small clusters during pulsed ablation of two binary semiconductors, zinc oxide and indium phosphide, in vacuum by UV, visible, and IR laser radiation is comparatively studied. The irradiation conditions favourable for generation of neutral and charged Zn{sub n}O{sub m} and In{sub n}P{sub m} clusters of different stoichiometry in the ablation products are found. The size and composition of the clusters, their expansion dynamics and reactivity are analysed by time-of-flight mass spectrometry. A particular attention is paid to the mechanisms of ZnO and InP ablation as a function of laser fluence, with the use of different ablation models. It is established that ZnO evapourates congruently in a wide range of irradiation conditions, while InP ablation leads to enrichment of the target surface with indium. It is shown that this radically different character of semiconductor ablation determines the composition of the nanostructures formed: zinc oxide clusters are mainly stoichiometric, whereas In{sub n}P{sub m} particles are significantly enriched with indium. (photonics and nanotechnology)
Bulgakov, A V; Evtushenko, A B; Shukhov, Yu G [S S Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Ozerov, I; Marin, W [Universite de la Mediterranee, CINaM, UPR CNRS 3118, Marseille (France)
New Combined Laser Ablation Platform Determines Cell Wall Chemistry (Fact Sheet)
NREL has designed and developed a combined laser ablation/pulsed sample introduction/mass spectrometry platform that integrates pyrolysis and/or laser ablation with resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry. Using this apparatus, we can measure the cell wall chemical composition of untreated biomass materials. Understanding the chemical composition of untreated biomass is key to both the biochemical and thermochemical conversion of lignocellulosic biomass to biofuels. In the biochemical conversion process, the new technique provides a better understanding of the chemistry of lignin and will improve accessibility to plant sugars. In thermochemical conversion, the information provided by the new technique may help to reduce the formation of unwanted byproducts during gasification. NREL validated the ability of the system to detect pyrolysis products from plant materials using poplar, a potentially high-impact bioenergy feedstock. In the technique, biomass vapors are produced by laser ablation using the 3rd harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of helium, then skimmed and introduced into an ionization region. REMPI is used to ionize the vapors because it is highly sensitive for detecting lignin and aromatic metabolites. The laser ablation method was used to selectively volatilize specific plant tissues and detect lignin-based products from the vapors with enhanced sensitivity. This will allow the determination of lignin distribution in future biomass studies.
Not Available
The 8th International Conference on Laser Ablation (COLA' 05); Journal of Physics: Conference Series
Science Conference Proceedings (OSTI)
Laser ablation encompasses a wide range of delicate to extreme light interactions with matter that present considerably challenging problems for scientists to study and understand. At the same time, laser ablation also represents a basic process of significant commercial importance in laser material processing�defining a multi-billion dollar industry today. These topics were widely addressed at the 8th International Conference on Laser Ablation (COLA), held in Banff, Canada on 11�16 September 2005. The meeting took place amongst the majestic and natural beauty of the Canadian Rocky Mountains at The Banff Centre, where delegates enjoyed many inspiring presentations and discussions in a unique campus learning environment. The conference brought together world leading scientists, students and industry representatives to examine the basic science of laser ablation and improve our understanding of the many physical, chemical and/or biological processes driven by the laser. The multi-disciplinary research presented at the meeting underlies some of our most important trends at the forefront of science and technology today that are represented in the papers collected in this volume. Here you will find new processes that are producing novel types of nanostructures and nano-materials with unusual and promising properties. Laser processes are described for delicately manipulating living cells or modifying their internal structure with unprecedented degrees of control and precision. Learn about short-pulse lasers that are driving extreme physical processes on record-fast time scales and opening new directions from material processing applications. The conference papers further highlight forefront application areas in pulsed laser deposition, nanoscience, analytical methods, materials, and microprocessing applications.
Hess, Wayne P.; Herman, Peter R.; Bauerle, Dieter W.; Koinuma, Hideomi
Computational study of nanosecond pulsed laser ablation and the application to momentum coupling
Science Conference Proceedings (OSTI)
During the evaporation and ablation of a matter induced by intensive laser radiation, the vapor plasma is ejected from the surface of the target which induces the recoil pressure and impulse in the target. Impulse coupling of laser beams with matter has been extensively studied as the basis of laser propulsion and laser clearing space debris. A one-dimensional (1D) bulk absorption model to simulate the solid target ablated directly by the laser beam is presented; numerical calculation of impulse acting on the target in vacuum with different laser parameters is performed with fluid dynamics theory and 1D Lagrange difference scheme. The calculated results of the impulse coupling coefficients are in good agreement with the experimental results and Phipps' empirical value. The simulated results show that the mechanical coupling coefficients decrease with the increment of laser intensity when the laser pulses generate plasma. The present model can be applied when the laser intensity is 10{sup 8} - 10{sup 10} W/cm{sup 2}, which will provide a guide to the study of momentum coupling of laser beams with matter.
Yuan Hong; Tong Huifeng; Li Mu; Sun Chengwei [Institute of Fluid Physics, Chinese Academy of Engineering Physics, P.O. Box 919-113, Mianyang, Sichuan 621900 (China)
ZnO clusters: Laser ablation production and time-of-flight mass spectroscopic study
Science Conference Proceedings (OSTI)
Zinc oxide clusters have been produced by laser ablation of bulk powder zinc peroxide in vacuum and investigated by time-of-flight mass spectroscopy. Experimental results revealed unpredicted and hitherto unknown (ZnO)"n clusters of enhanced stability ... Keywords: Cluster, Magic number, Time-of-flight mass spectroscopy, Zinc oxide
A. Dmytruk; I. Dmitruk; I. Blonskyy; R. Belosludov; Y. Kawazoe; A. Kasuya
Molecular dynamics study of nanoparticle evolution in a background gas under laser ablation,7] are used to explain the evaporationcondensation process. Molecular dynamics (MD) method [4,5,8,9] directly simulates molecular movement and interactions and can be used to investigate the evaporation process
Zhigilei, Leonid V.
A technique that combines the diagnostics of electron temperature history and the measurements of ablation velocity with two-tracer x-ray spectroscopy has been developed for diagnosing the temperature profiles in the thermal conduction layers of laser-ablated plastic foils. The electron temperature in the plastic ablator was diagnosed using the isoelectronic line ratios of Al Ly{alpha} line to Mg Ly{alpha} line, emitted from a tracer layer of Al/Mg mixture buried under the ablator. The ablation velocity was inferred from the time delay between the onset time of x-ray line emissions from Al and Mg tracer layers buried at two depths in the ablator, respectively. From the measured electron temperatures and ablation velocity, the electron temperature profile in the conduction layer was inferred. The measured temperature profile was compared with the simulated one and reasonable agreement was found.
Zhang Jiyan; Yang Guohong; Hu Xin; Yang Jiamin; Ding Yaonan; Ding Yongkun; Zhang Baohan; Zheng Zhijian [Research Center of Laser Fusion, P. O. Box 919-986, Mianyang 621900 (China); Xu Yan; Yan Jun; Pei Wenbin [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
Science Conference Proceedings (OSTI)
Time resolved signals in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are studied to determine the influence of experimental parameters on ICP-induced fractionation effects. Differences in sample composition and morphology, i.e., ablating brass, glass, or dust pellets, have a profound effect on the time resolved signal. Helium transport gas significantly decreases large positive signal spikes arising from large particles in the ICP. A binder for pellets also reduces the abundance and amplitude of spikes in the signal. MO{sup +} ions also yield signal spikes, but these MO{sup +} spikes generally occur at different times from their atomic ion counterparts.
Perdian, D.; Bajic, S.; Baldwin, D.; Houk, R.
Femtosecond pulse laser ablation of aluminum under different ambient air pressures between 1 atm and 4 x 10{sup -4} Pa is investigated using a femtosecond time-resolved shadowgraphic method. It is observed that as the ambient air pressure decreases, the contact front becomes more and more distinct for a certain pressure range, demonstrating that the confinement effect of the ambient air to the ablated target material can play a critically important role in the laser ablation process. It is also found that the concentric and semicircular stripe pattern, which results from the diffraction of the probe beam by the expanding plume of a specific material state and is typically observed in the shadowgraphs for 1-2 ns delay time, gradually blurs and disappears while the ambient air pressure decreases from 1 atm to 7000 Pa. If a prepulse or a relatively large pulse pedestal exists before the main pulse, however, the stripe pattern can still be observed even though the ambient air pressure is 5 x 10{sup -4} Pa. It is thus inferred that what contributes to the formation of the unique stripe pattern is a mixture of the ejected target material and ionized background gas induced by the femtosecond laser ablation.
Wu Zehua; Zhu Xiaonong; Zhang Nan
Production of copper and brass nanoparticles upon laser ablation in liquids
The production of nanoparticles upon ablation of copper and brass by pulsed radiation from Nd:YAG and copper lasers in water, ethanol, and acetone is studied. The nanoparticles were investigated by the methods of X-ray diffractometry, optical spectroscopy, and transmission electron microscopy. The produced copper and brass nanoparticles were shown to exhibit a plasmon resonance lying in the visible spectral range near 580 and 510 nm. The brass nanoparticles produced by ablation in ethanol have a shell approximately 10-nm thick for an average dimension of 20-30 nm. A chemical modification of ethanol was observed, which manifested itself in the appearance of intense UV absorption bands. Upon laser irradiation of brass nanoparticles in a liquid their absorption spectrum gradually transformed into the spectrum of copper nanoparticles. (interaction of laser radiation with matter)
Kazakevich, Pavel V; Simakin, Aleksandr V; Shafeev, Georgii A [Scientific Center for Wave Studies, A.M.Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Voronov, Valerii V [Laser Materials and Technology Research Center, A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Broadening of the spectral lines of a buffer gas and target substance in laser ablation
The broadening of discrete spectral lines from the plasma produced in the laser ablation of metal targets in a broad pressure range (10{sup 2} - 10{sup 7} Pa) of the ambient gas (Ar, He, H{sub 2}) was studied experimentally. The behaviour of spectral line broadening for the buffer gases was found to be significantly different from that for the atoms and ions of the target material. In comparison with target atoms, the atoms of buffer gases radiate from denser plasma layers, and their spectral line profiles are complex in shape. (interaction of laser radiation with matter. laser plasma)
Kask, Nikolai E; Michurin, Sergei V [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.
Ma Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu Jin [Universite de Lyon, F-69622, Lyon, France, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Lei Wenqi; Bai Xueshi; Zheng Lijuan; Zeng Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai (China)
Surface chemical reaction of laser ablated aluminum sample for detonation initiation
Science Conference Proceedings (OSTI)
We explore the evolution of metal plasma generated by high laser irradiances and its effect on the surrounding air by using shadowgraph images after laser pulse termination; hence the formation of laser supported detonation and combustion processes has been investigated. The essence of the paper is in observing initiation of chemical reaction between ablated aluminum plasma and oxygen from air by inducing high power laser pulse (>1000 mJ/pulse) and conduct a quantitative comparison of chemically reactive laser initiated waves with the classical detonation of exploding aluminum (dust) cloud in air. Findings in this work may lead to a new method of initiating detonation from metal sample in its bulk form without the need of mixing nano-particles with oxygen for initiation.
Kim, Chang-hwan; Yoh, Jack J. [School of Mechanical and Aerospace Engineering, Seoul National University, 599 Kwanakro, Kwanakgu, Seoul, Korea 151-742 (Korea, Republic of)
Guiding of 35 TW laser pulses in ablative capillary discharge waveguides
Science Conference Proceedings (OSTI)
An ablatively driven capillary discharge plasma waveguide has been used to demonstrate guiding of 30 fs, 35 TW laser pulses over distances up to 3 cm with incident intensity in excess of 4x10{sup 18} W/cm{sup 2}. The plasma density range over which good guiding was observed was 1-3x10{sup 18} cm{sup -3}. The quality of the laser spot at the exit mode was observed to be similar to that at the entrance and the transmitted energy was {approx}25% at input powers of 35 TW. The transmitted laser spectrum typically showed blueshifting due to ionization of carbon and hydrogen atoms in the capillary plasma by the high intensity laser pulse. The low plasma density regime in which these capillaries operate makes these devices attractive for use in single stage electron accelerators to multi-GeV energies driven by petawatt class laser systems.
McGuffey, C.; Matsuoka, T.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Levin, M.; Zigler, A. [Hebrew University, Jerusalem 91904 (Israel)
Velocity distribution measurements in atomic beams generated using laser induced back-ablation
We present measurements of the velocity distribution of calcium atoms in an atomic beam generated using a dual-stage laser back-ablation apparatus. Distributions are measured using a velocity selective Doppler time-of-flight technique. They are Boltzmann-like with rms velocities corresponding to temperatures above the melting point for calcium. Contrary to a recent report in the literature, this method does not generate a sub-thermal atomic beam.
Denning, A; Lee, S; Ammonson, M; Bergeson, S D
Synthesis of higher diamondoids by pulsed laser ablation plasmas in supercritical CO{sub 2}
Science Conference Proceedings (OSTI)
Pulsed laser ablation (wavelength 532 nm; fluence 18 J/cm{sup 2}; pulse width 7 ns; repetition rate 10 Hz) of highly oriented pyrolytic graphite was conducted in adamantane-dissolved supercritical CO{sub 2} with and without cyclohexane as a cosolvent. Micro-Raman spectroscopy of the products revealed the presence of hydrocarbons possessing sp{sup 3}-hybridized carbons similar to diamond structures. The synthesis of diamantane and other possible diamondoids consisting of up to 12 cages was confirmed by gas chromatography-mass spectrometry. Furthermore, gas chromatography-mass spectrometry measurements of samples before and after pyrolysis treatment indicate the synthesis of the most compact decamantane, namely, superadamantane. It is thought that oxidant species originating from CO{sub 2} during pulsed laser ablation might lead to the selective dissociation of C-H bonds, enabling the synthesis of low H/C ratio molecules. Therefore, laser ablation in supercritical CO{sub 2} is proposed as a practical method for synthesizing diamondoids.
Nakahara, Sho; Stauss, Sven; Kato, Toru; Terashima, Kazuo [Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8561 Chiba (Japan); Sasaki, Takehiko [Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8561 Chiba (Japan)
We investigated spatio-temporal evolution of ns laser ablation plumes at atmospheric pressure, a favored condition for laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass-spectrometry. The 1064 nm, 6 ns pulses from a Nd:YAG laser were focused on to an Al target and the generated plasma was allowed to expand in 1 atm Ar. The hydrodynamic expansion features were studied using focused shadowgraphy and gated 2 ns self-emission visible imaging. Shadowgram images showed material ejection and generation of shock fronts. A secondary shock is observed behind the primary shock during the time window of 100-500 ns with instabilities near the laser cone angle. By comparing the self-emission images obtained using fast photography, it is concluded that the secondary shocks observed in the shadowgraphy were generated by fast moving target material. The plume front estimates using fast photography exhibited reasonable agreement with data obtained from shadowgraphy at early times {<=}400 ns. However, at later times, fast photography images showed plume confinement while the shadowgraphic images showed propagation of the plume front even at greater times. The structure and dynamics of the plume obtained from optical diagnostic tools were compared to numerical simulations. We have shown that the main features of plume expansion in ambient Ar observed in the experiments can be reproduced using a continuum hydrodynamics model which provided valuable insight into the expansion dynamics and shock structure of the plasma plume.
Harilal, S. S.; Miloshevsky, G. V.; Diwakar, P. K.; LaHaye, N. L.; Hassanein, A. [Center for Materials under Extreme Environment, and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
Usage Of Polyacetal Powders As Laser Ablation Propulsion Propellants
Science Conference Proceedings (OSTI)
We examined impulse characteristics of polyoxymeythylene (POM) powders under irradiation by a TEA (Transversely-Excited at Atmospheric pressure)CO{sub 2} laser pulse. The impulse performance exhibited large scatter due to splashing particles. When the powder was hydraulically compacted to form a disk, the momentum coupling coefficient became comparable with that for bulk material, but the mass consumption was increased by several times.
Sasoh, Akihiro; Ogita, Naoya [Department of Aerospace Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Sinko, John E. [Micro-Nano Global Center of Excellence, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)
CO{sub 2} Laser Ablation Propulsion Area Scaling With Polyoxymethylene Propellant
The topic of area scaling is of great importance in the laser propulsion field, including applications to removal of space debris and to selection of size ranges for laser propulsion craft in air or vacuum conditions. To address this issue experimentally, a CO{sub 2} laser operating at up to 10 J was used to irradiate targets. Experiments were conducted in air and vacuum conditions over a range of areas from about 0.05-5 cm{sup 2} to ablate flat polyoxymethylene targets at several fluences. Theoretical effects affecting area scaling, such as rarefaction waves, thermal diffusion, and diffraction, are discussed in terms of the experimental results. Surface profilometry was used to characterize the ablation samples. A CFD model is used to facilitate analysis, and key results are compared between experimental and model considerations. The dependence of key laser propulsion parameters, including the momentum coupling coefficient and specific impulse, are calculated based on experimental data, and results are compared to existing literature data.
Sinko, John E. [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 (Japan); Ichihashi, Katsuhiro; Ogita, Naoya; Sakai, Takeharu; Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 (Japan); Tsukiyama, Yosuke [Micro-Nano Global Center of Excellence, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 (Japan); Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 (Japan); Umehara, Noritsugu [Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 (Japan)
Science Conference Proceedings (OSTI)
An improved microfabrication method was used to fabricate a continuous-flow PCR (polymerase chain reaction) microfluidic chip on the PMMA substrate using the low-power CO2 laser ablation technique. The use of the low-power CO2 laser ...
Heng Qi; Xiansong Wang; Tao Chen; Xuemei Ma; Tiechuan Zuo
A quantum model is proposed to investigate femtosecond laser pulse trains processing of dielectrics by including the plasma model with the consideration of laser particle-wave duality. Central wavelengths (400 nm and 800 nm) strongly impact the surface plasmon field distribution, the coupling field intensity distribution (between the absorbed intensity and the surface plasma), and the distribution of transient localized free electron density in the material. This, in turn, significantly changes the localized transient optical/thermal properties during laser materials processing. The effects of central wavelengths on ablation shapes and subwavelength ripples are discussed. The simulation results show that: (1) ablation shapes and the spacing of subwavelength ripples can be adjusted by localized transient electron dynamics control using femtosecond laser pulse trains; (2) the adjustment of the radii of ablation shapes is stronger than that of the periods of subwavelength ripples.
Yuan Yanping; Jiang Lan; Li Xin; Wang Cong [Laser Micro/Nano-Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China); Lu Yongfeng [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511 (United States)
Science Conference Proceedings (OSTI)
Pulsed laser ablation of solids in supercritical media has a large potential for nanomaterials fabrication. We investigated plasmas generated by pulsed laser ablation of Ni targets in CO{sub 2} at pressures ranging from 0.1 to 16 MPa at 304.5 K. Plasma species were characterized by optical emission spectroscopy, and the evolution of cavitation bubbles and shockwaves were observed by time-resolved shadowgraph imaging. Ni and O atomic emissions decreased with increasing gas pressure; however, near the critical point the intensities reached local maxima, probably due to the enhancement of the plasma excitation and effective quenching resulting from the large density fluctuation.
Kato, Toru; Stauss, Sven; Kato, Satoshi; Urabe, Keiichiro; Terashima, Kazuo [Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Baba, Motoyoshi; Suemoto, Tohru [Division of Advanced Spectroscopy, Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
Science Conference Proceedings (OSTI)
We investigated the spatial and temporal evolution of temperature and electron density associated with femto- and nanosecond laser-produced plasmas (LPP) from brass under similar laser fluence conditions. For producing plasmas, brass targets were ablated in vacuum employing pulses either from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) or from a Nd:YAG laser (6 ns, 1064 nm). Optical emission spectroscopy is used to infer the density and temperature of the plasmas. The electron density (n{sub e}) was estimated using Stark broadened profiles of isolated lines while the excitation temperature (T{sub exc}) was estimated using the Boltzmann plot method. At similar fluence levels, continuum and ion emission are dominant in ns LPP at early times (<50 ns) followed by atomic emission, while the fs LPP provided an atomic plume throughout its visible emission lifetime. Though both ns and fs laser-plasmas showed similar temperatures ({approx}1 eV), the fs LPP is found to be significantly denser at shorter distances from the target surface as well as at early phases of its evolution compared to ns LPP. Moreover, the spatial extension of the plume emission in the visible region along the target normal is larger for fs LPP in comparison with ns LPP.
Verhoff, B.; Harilal, S. S.; Freeman, J. R.; Diwakar, P. K.; Hassanein, A. [Center for Materials Under Extreme Environment and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
Science Conference Proceedings (OSTI)
Laser Ablation Absorbance Ratio Spectrometry (LAARS) is a new verification measurement technology under development at the US Department of Energy�s (DOE) Pacific Northwest National Laboratory (PNNL). LAARS uses three lasers to ablate and then measure the relative isotopic abundance of uranium compounds. An ablation laser is tightly focused on uranium-bearing solids producing a small plume containing uranium atoms. Two collinear wavelength-tuned spectrometry lasers transit through the plume and the absorbance of U-235 and U-238 isotopes are measured to determine U-235 enrichment. The measurement has high relative precision and detection limits approaching the femtogram range for uranium. It is independent of chemical form and degree of dilution with nuisance dust and other materials. High speed sample scanning and pinpoint characterization allow measurements on millions of particles/hour to detect and analyze the enrichment of trace uranium in samples. The spectrometer is assembled using commercially available components at comparatively low cost, and features a compact and low power design. Future designs can be engineered for reliable, autonomous deployment within an industrial plant environment. Two specific applications of the spectrometer are under development: 1) automated unattended aerosol sampling and analysis and 2) on-site small sample destructive assay measurement. The two applications propose game-changing technological advances in gaseous centrifuge enrichment plant (GCEP) safeguards verification. The aerosol measurement instrument, LAARS-environmental sampling (ES), collects aerosol particles from the plant environment in a purpose-built rotating drum impactor and then uses LAARS-ES to quickly scan the surface of the impactor to measure the enrichments of the captured particles. The current approach to plant misuse detection involves swipe sampling and offsite analysis. Though this approach is very robust it generally requires several months to obtain results from a given sample collection. The destructive assay instrument, LAARS-destructive assay (DA), uses a simple purpose-built fixture with a sampling planchet to collect adsorbed UF6 gas from a cylinder valve or from a process line tap or pigtail. A portable LAARS-DA instrument scans the microgram quantity of uranium collected on the planchet and the assay of the uranium is measured to ~0.15% relative precision. Currently, destructive assay samples for bias defect measurements are collected in small sample cylinders for offsite mass spectrometry measurement.
Anheier, Norman C.; Cannon, Bret D.; Qiao, Hong (Amy); Phillips, Jon R.
CO{sub 2} laser pulse shortening by laser ablation of a metal target
Science Conference Proceedings (OSTI)
A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO{sub 2} laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to {approx}2 ns and to remove the low power, long duration tails that are present in TEA CO{sub 2} pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is {approx}10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.
Donnelly, T.; Mazoyer, M.; Lynch, A.; O'Sullivan, G.; O'Reilly, F.; Dunne, P.; Cummins, T. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
Science Conference Proceedings (OSTI)
We present the results of our investigation on metallic films as suitable photocathodes for the production of intense electron beams in RF photoinjector guns. Pulsed laser ablation deposition technique was used for growing Mg and Y thin films onto Si and Cu substrates in high vacuum and at room temperature.Different diagnostic methods were used to characterize the thin films deposited on Si with the aim to optimize the deposition process. Photoelectron performances were investigated on samples deposited on Cu substrate in an ultra high vacuum photodiode chamber at 10{sup -7} Pa. Relatively high quantum efficiencies have been obtained for the deposited films, comparable to those of corresponding bulks. Samples could stay for several months in humid open air before being tested in a photodiode cell. The deposition process and the role of the photocathode surface contamination and its influence on the photoelectron performances are presented and discussed.
Fasano, V.; Lorusso, A.; Perrone, A. [National Institute of Nuclear Physics and Physics Department, University of Salento, Via Arnesano, 73100-Lecce (Italy); De Rosa, H. [Laboratorio de Metalografia, Dpto. Ingenieria Mecanica y Naval, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Cultrera, L. [National Institute of Nuclear Physics, National Laboratories, Frascati (Italy)
Angular distribution of atoms ejected by laser ablation of different metals
Science Conference Proceedings (OSTI)
Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm{sup 2}) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos{sup n} theta distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.
Konomi, I.; Motohiro, T. [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511 (Japan); Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Asaoka, T. [Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)
Quantum kinetic theory model of a continuous atom laser
We investigate the feasible limits for realising a continuously evaporated atom laser with high-temperature sources. A plausible scheme for realising a truly continuous atom laser is to outcouple atoms from a partially condensed Bose gas, whilst continuously reloading the system with non-condensed thermal atoms and performing evaporative cooling. Here we use quantum kinetic theory to model this system and estimate feasible limits for the operation of such a scheme. For sufficiently high temperatures, the figure of merit for the source is shown to be the phase-space flux. The dominant process limiting the usage of sources with low phase-space flux is the three-body loss of the condensed gas. We conclude that certain double-magneto-optical trap (MOT) sources may produce substantial mean condensate numbers through continuous evaporation, and provide an atom laser source with a narrow linewidth and reasonable flux.
G. R. Dennis; Matthew J. Davis; J. J. Hope
Isotope Enrichment Detection by Laser Ablation - Dual Tunable Diode Laser Absorption Spectrometry
Science Conference Proceedings (OSTI)
The rapid global expansion of nuclear energy is motivating the expedited development of new safeguards technology to mitigate potential proliferation threats arising from monitoring gaps within the uranium enrichment process. Current onsite enrichment level monitoring methods are limited by poor sensitivity and accuracy performance. Offsite analysis has better performance, but this approach requires onsite hand sampling followed by time-consuming and costly post analysis. These limitations make it extremely difficult to implement comprehensive safeguards accounting measures that can effectively counter enrichment facility misuse. In addition, uranium enrichment by modern centrifugation leads to a significant proliferation threat, since the centrifuge cascades can quickly produce a significant quantity of highly enriched uranium (HEU). The Pacific Northwest National Laboratory is developing an engineered safeguards approach having continuous aerosol particulate collection and uranium isotope analysis to provide timely detection of HEU production in a low enriched uranium facility. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy, to characterize the 235U/238U isotopic ratio by subtle differences in atomic absorption wavelengths arising from differences in each isotope�s nuclear mass, volume, and spin (hyperfine structure for 235U). Environmental sampling media is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes a 10 to 20-�m sample diameter. The ejected plasma forms a plume of atomic vapor. A plume for a sample containing uranium has atoms of the 235U and 238U isotopes present. Tunable diode lasers are directed through the plume to selectively excite each isotope and their presence is detected by monitoring absorbance signals on a shot-to-shot basis. Single-shot detection sensitivity approaching the femtogram range and abundance uncertainty less than 10% have been demonstrated with measurements on surrogate materials. In this paper we present measurement results on samples containing background materials (e.g., dust, minerals, soils) laced with micron-sized target particles having isotopic ratios ranging from 1 to 50%.
Anheier, Norman C.; Bushaw, Bruce A.
Langmuir probes (LP) are used extensively to characterize plasma environments produced by radio frequency, pulsed plasma thrusters, and laser ablation. We discuss here the development of a LP diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/{micro}s, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.
Patterson, J R; Emig, J A; Fournier, K B; Jenkins, P P; Trautz, K M; Seiler, S W; Davis, J F
Science Conference Proceedings (OSTI)
Investigate particles produced by laser irradiation and their analysis by Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA/ICP-MS), with a view towards optimizing particle production for analysis of high level waste materials and waste glass. LA/ICP-MS has considerable potential to increase the safety and speed of analysis required for the remediation of high level wastes from cold war plutonium production operations. In some sample types, notably the sodium nitrate-based wastes at Hanford and elsewhere, chemical analysis using typical laser conditions depends strongly on the details of sample history composition in a complex fashion, rendering the results of analysis uncertain. Conversely, waste glass materials appear to be better behaved and require different strategies to optimize analysis.
J. Thomas Dickinson; Michael L. Alexander
20, 171 5. K. Jain, Excimer laser lithography (SPIE OpticalGijbels, F. Adams (Eds. ), Laser Ionization Mass Analysis (G. Befeki, Principles of laser plasmas (Wiley Interscience,
Zeng, Xianzhong
In the present study, the ablation behavior of aluminum target and its plasma radiation in noble ambient gases by a laser pulse with wavelength of 266 nm and pulse duration of 10 ns are numerically studied. A thermal model of laser ablation considering heat conduction, Euler equations, Saha-Eggert equations, Knudsen layer, mass and energy balance relations and optical shielding effects are used for calculation of plasma parameters. Effects of excitation energy on plasma expansion and its emissivity are investigated. Time and spatial-resolved plasma emission including bremsstrahlung, recombination and spectral emission at early delay times after laser irradiation is obtained. Effects of two ambient gases (He and Ar) as well as different gas pressures of 100, 300, 500, and 760 Torr on plasma expansion and its spectrum are studied. Results illustrate that at initial delay times, especially at high noble gas pressures, ionic lines have the maximum intensities, while at later times neutral lines dominate. When the pressure of ambient gas increases, a confinement of the plasma plume is predicted and the intensity of neutral lines decreases. Continuous emission increases with wavelength in both ambient gases. Spatially resolved analysis shows that an intense continuous emission is predicted next to the sample surface decreasing with distance from the latter.
Rezaei, F.; Tavassoli, S. H. [Laser and Plasma Research Institute, ShahidBeheshti University, 19396 4716, G. C., Evin, Tehran (Iran, Islamic Republic of)
The global expansion of nuclear power, and consequently the uranium enrichment industry, requires the development of new safeguards technology to mitigate proliferation risks. Current enrichment monitoring instruments exist that provide only yes/no detection of highly enriched uranium (HEU) production. More accurate accountancy measurements are typically restricted to gamma-ray and weight measurements taken in cylinder storage yards. Analysis of environmental and cylinder content samples have much higher effectiveness, but this approach requires onsite sampling, shipping, and time-consuming laboratory analysis and reporting. Given that large modern gaseous centrifuge enrichment plants (GCEPs) can quickly produce a significant quantity (SQ ) of HEU, these limitations in verification suggest the need for more timely detection of potential facility misuse. The Pacific Northwest National Laboratory (PNNL) is developing an unattended safeguards instrument concept, combining continuous aerosol particulate collection with uranium isotope assay, to provide timely analysis of enrichment levels within low enriched uranium facilities. This approach is based on laser vaporization of aerosol particulate samples, followed by wavelength tuned laser diode spectroscopy to characterize the uranium isotopic ratio through subtle differences in atomic absorption wavelengths. Environmental sampling (ES) media from an integrated aerosol collector is introduced into a small, reduced pressure chamber, where a focused pulsed laser vaporizes material from a 10 to 20-�m diameter spot of the surface of the sampling media. The plume of ejected material begins as high-temperature plasma that yields ions and atoms, as well as molecules and molecular ions. We concentrate on the plume of atomic vapor that remains after the plasma has expanded and then cooled by the surrounding cover gas. Tunable diode lasers are directed through this plume and each isotope is detected by monitoring absorbance signals on a shot-to-shot basis. The media is translated by a micron resolution scanning system, allowing the isotope analysis to cover the entire sample surface. We also report, to the best of our knowledge, the first demonstration of laser-based isotopic measurements on individual micron-sized particles that are minor target components in a much larger heterogeneous mix of �background� particles. This composition is consistent with swipe and environmental aerosol samples typically collected for safeguards ES purposes. Single-shot detection sensitivity approaching the femtogram range and relative isotope abundance uncertainty better than 10% has been demonstrated using gadolinium isotopes as surrogate materials.
Anheier, Norman C.; Bushaw, Bruce A.
Methods for measurement of heterogeneous materials with laser-induced breakdown spectroscopy (LIBS)
from laser ablation of brass. Analytical Chemistry, vol. 77,femtosecond laser ablation of brass: particulate and ICPMSand nanosecond laser ablation of brass. Journal Analytical
Effenberger, Andrew Jay
Angular distributions of atoms emitted by laser ablation of perovskite-type oxide SrZrO{sub 3} have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy and charge-coupled device photography with an interference filter. Each constituent element has been analyzed as a two-modal distribution composed of a broad cos{sup m} {theta} distribution and a narrow cos{sup n} {theta} distribution. The exponent n characterizes the component of laser ablation while the exponent m characterizes that of thermal evaporation, where a larger n or m means a narrower angular distribution. In vacuum, O (n=6) showed a broader distribution than those of Sr (n=16) and Zr (n=17), and Sr{sup +} exhibited a spatial distribution similar to that of Sr. As the laser fluence was increased from 1.1 to 4.4 J/cm{sup 2}, the angular distribution of Sr became narrower. In the laser fluence range of 1.1-4.4 J/cm{sup 2}, broadening of the angular distribution of Sr was observed only at the fluence of 1.1 J/cm{sup 2} under the oxygen pressure of 10 Pa. Monte Carlo simulations were performed to estimate approximately the energy of emitted atoms, focusing on the broadening of the angular distribution under the oxygen pressure of 10 Pa. The energies of emitted atoms were estimated to be 1-20 eV for the laser fluence of 1.1 J/cm{sup 2}, and more than 100 eV for 2.2 and 4.4 J/cm{sup 2}.
Konomi, I.; Motohiro, T.; Azuma, H.; Asaoka, T.; Nakazato, T.; Sato, E.; Shimizu, T.; Fujioka, S.; Sarukura, N.; Nishimura, H. [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku-ku, Nagoya 468-8511, Japan and Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)
Expansion of the laser ablation vapor plume into a background gas: Part A, Analysis
x ] = 1 y 2 y 4 dy The thermal energy stored in the vaporet + E ek (subscript t=thermal energy and k=kinetic energy)Also, the kinetic and thermal energies in the vapor plume
Wen, Sy-Bor; Mao, Xianglei; Greif, Ralph; Russo, Richard E.
High throughput solar cell ablation system
A solar cell is formed using a solar cell ablation system. The ablation system includes a single laser source and several laser scanners. The laser scanners include a master laser scanner, with the rest of the laser scanners being slaved to the master laser scanner. A laser beam from the laser source is split into several laser beams, with the laser beams being scanned onto corresponding wafers using the laser scanners in accordance with one or more patterns. The laser beams may be scanned on the wafers using the same or different power levels of the laser source.
Harley, Gabriel; Pass, Thomas; Cousins, Peter John; Viatella, John
Atomic-Scale Structure of Al2O3-ZrO2 Mixed Oxides Prepared by Laser Ablation
Science Conference Proceedings (OSTI)
By means of x-ray diffractometry (XRD) and X-ray absorption fine structure spectroscopy, the phase composition and atomic structure of laser evaporated ZrO2 and ZrO2-Al2O3 nanopowders have been studied. The results indicate that pure ZrO2 exists in the form of tetragonal structure, Al2O3 doped ZrO2 nanoparticles, however, have cubic structure. Compared to bulk tetragonal ZrO2, pure tetragonal ZrO2 nanoparticles have a shorter Zr-O- and Zr-Zr shell, indicating that the lattice contracts with decreasing particle size. For Al2O3 doped ZrO2 solid solution, the distances of first Zr-O and Zr-Zr (Al) coordination decrease with increasing solid solubility. The disorder degree of the ZrO2 lattice increases with increasing solid solubility. The coevaporated ZrO2-Al2O3 is quickly solidified into amorphous phase when it is ablated in a higher pressure. The amorphous phase contains Zr-O-Zr (Al) clusters and has shorter Zr-O distance and tower Zr-O coordination number.
Yang Xiuchun [College of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Dubiel, M. [Department of Physics, Martin Luther University of Halle, D-06108 Halle (Germany); Hofmeister, H. [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Riehemann, W. [Department of Materials Science and Engineering, Clausthal University of Technology (Germany)
An electronic device is described which generates a delayed pulse, where the delay is increased in a step-like manner. This device finds application in the measurement of kinetic decays, particularly when laser-induced fluorescent (LIF) detection of the decaying species is used. The circuit uses 15 low-power Schottky TTL chips and is contained within a dual width NIM module.
Halpern, J.B.; Towns, T.G.
Convergent ablator performance measurements
Science Conference Proceedings (OSTI)
The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile {rho}(r) and effective backlighter profile I{sub 0}(y) at each time step to be uniquely determined subject to the constraints that {rho}(r) is localized in radius space and I{sub 0}(y) is delocalized in object space. Moments of {rho}(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].
Hicks, D. G.; Spears, B. K.; Braun, D. G.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Olson, R. E. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
Angular emission of ions and mass deposition from femtosecond and nanosecond laser-produced plasmas
We investigated the angular distribution of ions and atoms emanating from femto- and nanosecond laser-produced metal plasmas under similar laser fluence conditions. For producing plasmas, aluminum targets are ablated in vacuum employing pulses from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) and an Nd:YAG laser (6 ns, 1064 nm). The angular distribution of ion emission as well as the kinetic energy distribution is characterized by a Faraday cup, while a quartz microbalance is used for evaluating deposited mass. The ion and deposited mass features showed that fs laser ablated plasmas produced higher kinetic energy and more mass per pulse than ns plumes over all angles. The ion flux and kinetic energy studies show fs laser plasmas produce narrower angular distribution while ns laser plasmas provide narrower energy distribution.
Verhoff, B.; Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.
This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.
This dissertation focused on new applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The diverse fields that were investigated show the versatility of the technique. In Chapter 2, LA-ICP-MS was used to investigate the rare earth element (REE) profiles of garnets from the Broken Hill Deposit in New South Wales, Australia. The normalized REE profiles helped to shed new light on the formation of deposits of sulfide ores. This information may be helpful in identifying the location of sulfide ore deposits in other locations. New sources of metals such as Pg, Zn, and Ag, produced from these ores, are needed to sustain our current technological society. The application of LA-ICP-MS presented in Chapter 3 is the forensics analysis of automotive putty and caulking. The elemental analysis of these materials was combined with the use of Principal Components Analysis (PCA). The PCA comparison was able to differentiate the automotive putty samples by manufacturer and lot number. The analysis of caulk was able to show a differentiation based on manufacturer, but no clear differentiation was shown by lot number. This differentiation may allow matching of evidence in the future. This will require many more analyses and the construction of a database made up of many different samples. The 4th chapter was a study of the capabilities of LA-ICP-MS for fast and precise analysis of particle ensembles for nuclear nonproliferation applications. Laser ablation has the ability to spatially resolve particle ensembles which may contain uranium or other actinides from other particles present in a sample. This is of importance in samples obtained from air on filter media. The particle ensembles of interest may be mixed in amongst dust and other particulates. A problem arises when ablating these particle ensembles directly from the filter media. Dust particles other than ones of interest may be accidentally entrained in the aerosol of the ablated particle ensemble. This would cause the analysis to be skewed. The use of a gelatin substrate allows the ablation a particle ensemble without disturbing other particles or the gelatin surface. A method to trap and ablate particles on filter paper using collodion was also investigated. The laser was used to dig through the collodion layer and into the particle ensemble. Both of these methods fix particles to allow spatial resolution of the particle ensembles. The use of vanillic acid as a possible enhancement to ablation was also studied. A vanillic acid coating of the particles fixed on top of the gelatin substrate was not found to have any positive effect on either signal intensity or precision. The mixing of vanillic acid in the collodion solution used to coat the filter paper increased ablation signal intensity by a factor of 4 to 5. There was little effect on precision, though. The collodion on filter paper method and the gelatin method of resolving particles have shown themselves to be possible tools in fighting proliferation of nuclear weapons and material. Future applications of LA-ICP-MS are only limited by the imagination of the investigator. Any material that can be ablated and aerosolized is a potential material for analysis by LA-ICP-MS. Improvements in aerosol transport, ablation chamber design, and laser focusing can make possible the ablation and analysis of very small amounts of material. This may perhaps lead to more possible uses in forensics. A similar method to the one used in Chapter 3 could perhaps be used to match drug residue to the place of origin. Perhaps a link could be made based on the elements leached from the soil by plants used to make drugs. This may have a specific pattern based on where the plant was grown. Synthetic drugs are produced in clandestine laboratories that are often times very dirty. The dust, debris, and unique materials in the lab environment could create enough variance to perhaps match drugs produced there to samples obtained off the street. Even if the match was not strong enough to be evidence, the knowledge that many sa
Messerly, Joshua D.
Hydrogen from Biomass Catalytic Reforming of Pyrolysis Vapors R. Evans, L. Boyd, C. Elam, S-23, 2003 #12;Project Goals Demonstrate the production of hydrogen from biomass by pyrolysis steam catalysts and reactor configuration for fluid bed reforming of biomass pyrolysis liquid at pilot scale (500
Feasibility Study on Laser Microwelding and Laser Shock Peening using Femtosecond Laser Pulses.
??Ultrafast lasers of sub-picosecond pulse duration have thus far been investigated for ablation, drilling and cutting processes. Ultrafast lasers also have the potential for laser� (more)
Lee, Dongkyun
This dissertation provides a general introduction to Inductively coupled plasma-mass spectrometry (ICP-MS) and laser ablation (LA) sampling, with an examination of analytical challenges in the employment of this technique. It discusses the origin of metal oxide ions (MO+) in LA-ICP-MS, as well as the effect of introducing helium and nitrogen to the aerosol gas flow on the formation of these polyatomic interferences. It extends the study of polyatomic ions in LA-ICP-MS to metal argide (MAr+) species, an additional source of possible significant interferences in the spectrum. It describes the application of fs-LA-ICP-MS to the determination of uranium isotope ratios in particulate samples.
Witte, Travis
0.374 Pflop/s trillion-particle kinetic modeling of laser plasma interaction on Roadrunner
Science Conference Proceedings (OSTI)
We demonstrate the outstanding performance and scalability of the VPIC kinetic plasma modeling code on the heterogeneous IBM Roadrunner supercomputer at Los Alamos National Laboratory. VPIC is a three-dimensional, relativistic, electromagnetic, particle-in-cell ... Keywords: heterogeneous architecture, high performance computing, inertial confinement fusion, laser plasma instability, memory management, particle in cell, petaflop
K. J. Bowers; B. J. Albright; B. Bergen; L. Yin; K. J. Barker; D. J. Kerbyson
Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species is described. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.
Cross, J.B.; Cremers, D.A.
Laser sustained discharge apparatus for the production of intense beams of high kinetic energy atomic species. A portion of the plasma resulting from a laser sustained continuous optical discharge which generates energetic atomic species from a gaseous source thereof is expanded through a nozzle into a region of low pressure. The expanded plasma contains a significant concentration of the high kinetic energy atomic species which may be used to investigate the interaction of surfaces therewith. In particular, O-atoms having velocities in excess of 3.5 km/s can be generated for the purpose of studying their interaction with materials in order to develop protective materials for spacecraft which are exposed to such energetic O-atoms during operation in low earth orbit.
Cross, Jon B. (Santa Fe, NM); Cremers, David A. (Los Alamos, NM)
review and evaluation of carbon dioxide laser vaporization.cauterization or fraxelated carbon dioxide (CO 2 ) laser wasand argon laser. Carbon dioxide laser ablation (10,600 nm)
Emer, Jason; Gropper, Jaime; Gallitano, Stephanie; Levitt, Jacob
Science Conference Proceedings (OSTI)
The texture of YBa{sub 2}Cu{sub 3}O{sub 7} thin films on (100) SrTiO{sub 3}, grown by {ital in} {ital situ} laser ablation, was investigated by x-ray diffraction. The surface morphology is smooth with only 10{sup 5} cm{sup {minus}2} particulates of about 0.1 {mu}m in diameter. High-resolution x-ray diffraction shows that the {ital c}-axis of YBa{sub 2}Cu{sub 3}O{sub 7} is epitaxially aligned with the (001) direction of SrTiO{sub 3} irrespective of the misorientation. The {l brace}018{r brace} pole figure of YBa{sub 2}Cu{sub 3}O{sub 7} shows a fourfold symmetry which indicates that the films are ordered with respect to the substrate lattice. Moreover, the alignment in the {l brace}018{r brace} pole figure of the (220) reflections of SrTiO{sub 3} and the (018) reflections of YBa{sub 2}Cu{sub 3}O{sub 7} indicates that over the whole surface of the film the {ital a}- and {ital b}-axes of YBa{sub 2}Cu{sub 3}O{sub 7} are aligned along the (100) and (010) direction of SrTiO{sub 3}. The epitaxial nature of the films, the low density of particulates, and the lack of interdiffusion as concluded from secondary ion mass spectrometry measurements, allows for the preparation of heteroepitaxial stacks containing high-{ital T}{sub {ital c}} superconductors.
Cillessen, J.F.M.; de Leeuw, D.M.; Kinneging, A.J.; Zalm, P.C.; Bongers, P.F. (Philips Research Laboratories, P.O. Box 80 000, 5600 JA Eindhoven, The Netherlands (NL))
Alopecia: A review of laser and light therapies
78. Smithdeal CD. Carbon dioxide laser-assisted hairusing the Ultrapulse carbon dioxide laser handpiece.loss. Starting in 1995, carbon dioxide laser tissue ablation
Rangwala, Sophia; Rashid, Rashid M
Streaked radiography measurements of convergent ablator performance (invited)
Science Conference Proceedings (OSTI)
The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other ablator rocket parameters have been measured using a single streaked x-ray radiograph. A regularization technique has been used to determine the ablator density profile {rho}(r) at each time step; moments of {rho}(r) then provide the areal density, average radius, and mass of the unablated, or remaining, ablator material, with the velocity determined from the time derivative of the average radius. The technique has been implemented on experiments at the OMEGA laser facility.
Hicks, D. G. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
Optimization of a kinetic laser-plasma interaction code for large parallel systems
Science Conference Proceedings (OSTI)
In this work, we simulate the interaction between intense laser radiation and a fully ionized plasma by solving a Vlasov-Maxwell system using the "Particle-In-Cell" (PIC) method. This method provides a very detailed description of the plasma dynamics, ... Keywords: PIC method, high-performance computing, parallel sparse solver
Olivier Coulaud; Micha�l Dussere; Pascal H�non; Erik Lefebvre; Jean Roman
Carbon Isotope Separation and Molecular Formation in Laser-Induced...
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Carbon Isotope Separation and Molecular Formation in Laser-Induced Plasmas by Laser Ablation Molecular Isotopic Spectrometry Title Carbon Isotope Separation and Molecular Formation...
Kinetics of laser pulse vaporization of uranium dioxide by mass spectrometry
Science Conference Proceedings (OSTI)
Safety analyses of nuclear reactors require knowledge of the evaporation behavior of UO/sub 2/ at temperatures well above the melting point of 3140 K. In this study, rapid transient heating of a small spot on a UO/sub 2/ specimen was accomplished by a laser pulse, which generates a surface temperature excursion. This in turn vaporizes the target surface and the gas expands into vacuum. The surface temperature transient was monitored by a fast-response automatic optical pyrometer. The maximum surface temperatures investigated range from approx. 3700 K to approx. 4300 K. A computer program was developed to simulate the laser heating process and calculate the surface temperature evolution. The effect of the uncertainties of the high temperature material properties on the calculation was included in a sensitivity study for UO/sub 2/ vaporization. The measured surface temperatures were in satisfactory agreements.
Tsai, C.
First, an introductory overview of the different types of laser propulsion techniques will be given and illustrated by some historical examples. Second, laser devices available for basic experiments will be reviewed ranging from low power lasers sources to inertial confinement laser facilities. Subsequently, a status of work will show the impasse in which the laser propulsion community is currently engaged. Revisiting the basic relations leads to new avenues in ablative and direct laser propulsion for ground based and space based applications. Hereby, special attention will be devoted to the impact of emerging ultra-short pulse lasers on the coupling coefficient and specific impulse. In particular, laser sources and laser propulsion techniques will be tested in microgravity environment. A novel approach to debris removal will be discussed with respect to the Satellite Laser Ranging (SRL) facilities. Finally, some non technical issues will be raised aimed at the future prospects of laser propulsion in the international community.
Bohn, Willy L. [Institute of Technical Physics, German Aerospace Center (DLR) D-70569 Pfaffenwaldring 38-40, Stuttgart (Germany)
An extensive set of laser-induced fluorescence (LIF) measurements of Si atoms during the chemical vapor deposition (CVD) of silicon from silane and disilane in a research rotating disk reactor are presented. The experimental results are compared in detail with predictions from a numerical model of CVD from silane and disilane that treats the fluid flow coupled to gas-phase and gas-surface chemistry. The comparisons showed that the unimolecular decomposition of SiH[sub 2] could not account for the observed gas-phase Si atom density profiles. The H[sub 3]SiSiH [leftrightarrow] Si + SiH[sub 4] and H[sub 3]SiSiH + SiH[sub 2] [leftrightarrow] Si + Si[sub 2]H[sub 6] reactions are proposed as the primary Si atom production routes. The model is in good agreement with the measured shapes of the Si atom profiles and the trends in Si atom density with susceptor temperature, pressure, and reactant gas mixture. 33 refs., 12 figs., 3 tabs.
Ho, P.; Coltrin, M.E.; Breiland, W.G. (Sandia National Lab., Albuquerque, NM (United States))
Some of the major applications of laser surgery involve the photocoagulation of diseased tissue, with minimal or no damage to the surrounding healthy tissue. There is a growing need for a model for the quantification of thermal damage. The models presently available in the literature assume biological tissue to be composed of a single component having a single rate of damage. But recent studies have shown that a distribution of rate parameters rather than a single rate parameter, best describes the process of thermal coagulation. This study assumes tissue to be composed of two or more components, having different rates of damage. The results of this model are then used to find an effective rate of damage for a single rate model which would yield the same end concentrations as the multi rate model. Results indicate that the difference between the single rate and the multi rate predictions is highly predominant for relatively lower power settings, for the biokinetic coefficient values used in this research. As the power is increased, a single rate model effectively describes a multi rate model, in the prediction of damage and movement of damage front. The movement of damage front was also studied experimentally using Digital Image Processing techniques. The damage model predicted by this study qualitatively follows the theoretical models available in the literature.
Azeemi, Aamer Amjed
The mechanism of thin film Si nanomachining using femtosecond laser pulses
Femtosecond (fs) laser ablation has been the subject of intense recent research. The pulse time ('width') is shorter than the electronic relaxation time, resulting in a decoupling of the period of laser illumination and ...
Jia, Jimmy Yi-Jie, 1980-
Recent laser-plasma interaction experiments at the Lawrence Livermore National Laboratory
Science Conference Proceedings (OSTI)
Recent Livermore experiments are aimed at investigating laser-plasma interaction issues which are relevant to ablatively driven fusion processes. We report the data obtained from using longer pulses and shorter laser wavelengths.
Lee, P.H.Y.
Nanometer-scale ablation using focused, coherent extreme ultraviolet/soft x-ray light
Ablation of holes having diameters as small as 82 nm and having clean walls was obtained in a poly(methyl methacrylate) on a silicon substrate by focusing pulses from a Ne-like Ar, 46.9 nm wavelength, capillary-discharge laser using a freestanding Fresnel zone plate diffracting into third order is described. Spectroscopic analysis of light from the ablation has also been performed. These results demonstrate the use of focused coherent EUV/SXR light for the direct nanoscale patterning of materials.
Menoni, Carmen S. (Fort Collins, CO); Rocca, Jorge J. (Fort Collins, CO); Vaschenko, Georgiy (San Diego, CA); Bloom, Scott (Encinitas, CA); Anderson, Erik H. (El Cerrito, CA); Chao, Weilun (El Cerrito, CA); Hemberg, Oscar (Stockholm, SE)
Laser Propulsion Standardization Issues
It is a relevant issue in the research on laser propulsion that experimental results are treated seriously and that meaningful scientific comparison is possible between groups using different equipment and measurement techniques. However, critical aspects of experimental measurements are sparsely addressed in the literature. In addition, few studies so far have the benefit of independent confirmation by other laser propulsion groups. In this paper, we recommend several approaches towards standardization of published laser propulsion experiments. Such standards are particularly important for the measurement of laser ablation pulse energy, laser spot area, imparted impulse or thrust, and mass removal during ablation. Related examples are presented from experiences of an actual scientific cooperation between NU and DLR. On the basis of a given standardization, researchers may better understand and contribute their findings more clearly in the future, and compare those findings confidently with those already published in the laser propulsion literature. Relevant ISO standards are analyzed, and revised formats are recommended for application to laser propulsion studies.
Scharring, Stefan; Eckel, Hans-Albert [Institute of Technical Physics, German Aerospace Center (DLR), D-70569 Stuttgart, Pfaffenwaldring 38-40 (Germany); Roeser, Hans-Peter [Institute of Space Systems, University of Stuttgart, D-70569 Stuttgart, Pfaffenwaldring 31 (Germany); Sinko, John E. [Micro-Nano Global Center of Excellence, Nagoya University (Niue), Nagoya, Aichi, 464-8603 (Japan); Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Nagoya, Aichi, 464-8603 (Japan)
Science Conference Proceedings (OSTI)
Two new experimental technologies enabled realization of Break-out afterburner (BOA) - High quality Trident laser and free-standing C nm-targets. VPIC is an powerful tool for fundamental research of relativistic laser-matter interaction. Predictions from VPIC are validated - Novel BOA and Solitary ion acceleration mechanisms. VPIC is a fully explicit Particle In Cell (PIC) code: models plasma as billions of macro-particles moving on a computational mesh. VPIC particle advance (which typically dominates computation) has been optimized extensively for many different supercomputers. Laser-driven ions lead to realization promising applications - Ion-based fast ignition; active interrogation, hadron therapy.
Wu, Hui-Chun [Los Alamos National Laboratory; Hegelich, B.M. [Los Alamos National Laboratory; Fernandez, J.C. [Los Alamos National Laboratory; Shah, R.C. [Los Alamos National Laboratory; Palaniyappan, S. [Los Alamos National Laboratory; Jung, D. [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory; Albright, B.J. [Los Alamos National Laboratory; Bowers, K. [Guest Scientist of XCP-6; Huang, C. [Los Alamos National Laboratory; Kwan, T.J. [Los Alamos National Laboratory
Commercial application of laser fusion
The fundamentals of laser-induced fusion, some laser-fusion reactor concepts, and attendant means of utilizing the thermonuclear energy for commercial electric power generation are discussed. Theoretical fusion-pellet microexplosion energy release characteristics are described and the effects of pellet design options on pellet-microexplosion characteristics are discussed. The results of analyses to assess the engineering feasibility of reactor cavities for which protection of cavity components is provided either by suitable ablative materials or by diversion of plasmas by magnetic fields are presented. Two conceptual laser-fusion electric generating stations, based on different laser-fusion reactor concepts, are described.
Booth, L.A.
Preheat effects on microballoon laser fusion implosions
Nonequilibrium hydroburn simulations of early laser-driven compression experiments indicate that low energy photons from the vicinity of the ablation surface are preheating the microballoon-pushers, thereby severely limiting the compressions achieved (similar degradation may result from 1 to 4 percent energy deposition by superthermal electrons). This implies an 8- to 27-fold increase in the energy requirements for breakeven, unless radiative preheat can be drastically reduced by, say, the use of composite ablator-pushers. (auth)
Fraley, G.S.; Mason, R.J.
Observation of the Rayleigh-Taylor instability in ablatively accelerated foils
We present the first absolute, two-dimensionally resolved measurements of areal mass density of laser-driven ablatively accelerated foils, which show the Rayleigh-Taylor instability developing from initial mass perturbations. Our data are near simulation results which predict that the Rayleigh-Taylor growth rate is less than classical. The measurements sometimes show development of significant areal mass inhomogeneity in a direction perpendicular to that of the initially imposed perturbations.
Grun, J.; Emery, M.H.; Kacenjar, S.; Opal, C.B.; McLean, E.A.; Obenschain, S.P.; Ripin, B.H.; Schmitt, A.
Simplified laser-driven flyer plates for shock compression science
Science Conference Proceedings (OSTI)
We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s{sup -1} and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.
Brown, Kathryn E.; Shaw, William L.; Zheng Xianxu; Dlott, Dana D. [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801 (United States)
Similar phase formation and crystallization behaviors have been observed in the a-Ge/Cu bilayer under thermal annealing and pulsed laser irradiation. The Cu{sub 3}Ge phase would form prior to the crystallization of a-Ge. The crystallization temperature and activation energy for crystallization of a-Ge were reduced to 310 deg. C and 2.75 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of {approx}2.0 for the a-Ge/Cu bilayer corresponds to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser irradiation, the maximum data-transfer-rates of 44, 56, 74, and 112 Mbit/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively. The a-Ge/Cu bilayer also demonstrated sufficient optical contrast and adequate absorptance for low power and high speed write-once blue-ray recording.
Her, Yung-Chiun; Tu, Wei-Ting; Tsai, Ming-Hsin [Department of Materials Science and Engineering, National Chung Hsing University, Taichung, Taiwan 40254 (China)
We study a minimalist kinetic model for economies. A system of agents with local trading rules display emergent demand behaviour. We examine the resulting wealth distribution to look for non-thermal behaviour. We compare and contrast this model with other similar models.
Abdullah, Wan Ahmad Tajuddin Wan
Laser-Induced Damage of Calcium Fluoride
Science Conference Proceedings (OSTI)
Radiation damage of materials has long been of fundamental interest, especially since the growth of laser technology. One such source of damage comes from UV laser light. Laser systems continue to move into shorter wavelength ranges, but unfortunately are limited by the damage threshold of their optical components. For example, semiconductor lithography is making its way into the 157nm range and requires a material that can not only transmit this light (air cannot), but also withstand the highly energetic photons present at this shorter wavelength. CaF2, an alkaline earth halide, is the chosen material for vacuum UV 157 nm excimer radiation. It can transmit light down to 120 nm and is relatively inexpensive. Although it is readily available through natural and synthetic sources, it is often times difficult to find in high purity. Impurities in the crystal can result in occupied states in the band gap that induce photon absorption [2] and ultimately lead to the degradation of the material. In order to predict how well CaF2 will perform under irradiation of short wavelength laser light, one must understand the mechanisms for laser-induced damage. Laser damage is often a two-step process: initial photons create new defects in the lattice and subsequent photons excite these defects. When laser light is incident on a solid surface there is an initial production of electron-hole (e-h) pairs, a heating of free electrons and a generation of local heating around optically absorbing centers [3]. Once this initial excitation converts to the driving energy for nuclear motion, the result is an ejection of atoms, ions and molecules from the surface, known as desorption or ablation [3]. Secondary processes further driving desorption are photoabsorption, successive excitations of self-trapped excitons (STE's) and defects, and ionization of neutrals by incident laser light [3]. The combination of laser-induced desorption and the alterations to the electronic and geometrical structure of the lattice result in defect formation. In the material CaF2 some of these defects take the form of F-centers, an electron trapped at a halogen vacancy [4], and H-centers, a F2- molecular ion at a single lattice site [5]. While the F-centers are stable, the H-centers are transient but can form into aggregates that are stable. There are many different configurations the defects can take based on the relative position of F and H centers in the lattice and this is extensively discussed in literature [1,4,5]. Once these defects have formed they cause further absorption of light, which ultimately induces particle emission and the production of even more defects. Various forms of laser-induced damage of CaF2 have been studied. For example, the mechanism for photon-stimulated desorption (PSD) of F+ from CaF2 (111) is discussed in ref. 6 and the energy threshold, distribution and kinetics governing electron-stimulated desorption (ESD) is investigated in ref. 7. The desorption of neutral Ca and F atoms has also been explored [1]. In this paper I focus on the emission of ions and neutrals from CaF2 under the irradiation of pulsed laser light at 266 nm, in addition to a brief study of its purity and transmittance.
Espana, Aubrey L.; Joly, Alan G.; Hess, Wayne P.; Dickinson, J T.
Towards Optimization of Probe Placement for Radio-Frequency Ablation
's electric potential and of the steady state of the heat distribution during RF ablation. The optimization of the optimization to artificial data and a comparison to a real RF ablation are presented. 1 Introduction on Cartesian or tetrahedral grids. In this work we consider the radio-frequency (RF) ablation of liver tumors
Preusser, Tobias
Synthesis of materials with infrared and ultraviolet lasers
This paper discusses three divergent examples of synthesis of materials with lasers. The three techniques are: (1) infrared (CO/sub 2/) laser synthesis of silane (SiH/sub 4/) from disilane (Si/sub 2/H/sub 6/); (2) excimer (ArF) laser production of fine silicon powders from methyl- and chloro-substituted silanes; and, (3) excimer (KrF) laser production of fine metallic powders by laser ablation. The mechanism for each process is discussed along with some conclusions about the features of the laser radiation that enable each application. 19 refs., 12 figs., 2 tabs.
Lyman, J.L.
Apparatus for the laser ablative synthesis of carbon nanotubes
An RF-induction heated side-pumped synthesis chamber for the production of carbon nanotubes. Such an apparatus, while capable of producing large volumes of carbon nanotubes, concurrently provides a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization.
Smith, Michael W. (Newport News, VA); Jordan, Kevin (Newport News, VA)
High density laser-driven target
A high density target for implosion by laser energy composed of a central quantity of fuel surrounded by a high-Z pusher shell with a low-Z ablator-pusher shell spaced therefrom forming a region filled with low-density material.
Lindl, John D. (San Ramon, CA)
Early stage expansion and time-resolved spectral emission of laser-induced
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Early stage expansion and time-resolved spectral emission of laser-induced Early stage expansion and time-resolved spectral emission of laser-induced plasma from polymer Title Early stage expansion and time-resolved spectral emission of laser-induced plasma from polymer Publication Type Journal Article Year of Publication 2009 Authors Boueri, Myriam, Matthieu Baudelet, Jin Yu, Xianglei Mao, Samuel S. Mao, and Richard E. Russo Journal Applied Surface Science Volume 255 Issue 24 Pagination 9566-9571 Date Published 09/2009 Keywords Early stage plasma expansion, Laser ablation of polymer, Plasma spectral emission Abstract In the nanosecond laser ablation regime, absorption of laser energy by the plasma during its early stage expansion critically influences the properties of the plasma and thus its interaction with ambient air. These influences can significantly alter spectral emission of the plasma. For organic samples especially, recombination of the plasma with the ambient air leads to interfering emissions with respect to emissions due to native species evaporated from the sample. Distinguishing interfering emissions due to ambient air represents a critical issue for the application of laser-induced breakdown spectroscopy (LIBS) to the analysis of organic materials. In this paper, we report observations of early stage expansion and interaction with ambient air of the plasma induced on a typical organic sample (nylon) using timeresolved shadowgraph. We compare, in the nanosecond ablation regime, plasmas induced by infrared (IR) laser pulses (1064 nanometers) and ultraviolet (UV) laser pulses (266 nanometers). Nanosecond ablation is compared with femtosecond ablation where the post-ablation interaction is absent. Subsequent to the early stage expansion, we observe for each studied ablation regime, spectral emission from CN, a typical radical for organic and biological samples. Time-resolved LIBS allows identifying emissions from native molecular species and those due to recombination with ambient air through their different time evolution behaviors.
Measurement Issues In Pulsed Laser Propulsion
Various measurement techniques have been used throughout the over 40-year history of laser propulsion. Often, these approaches suffered from inconsistencies in definitions of the key parameters that define the physics of laser ablation impulse generation. Such parameters include, but are not limited to the pulse energy, spot area, imparted impulse, and ablated mass. The limits and characteristics of common measurement techniques in each of these areas will be explored as they relate to laser propulsion. The idea of establishing some standardization system for laser propulsion data is introduced in this paper, so that reported results may be considered and studied by the general community with more certain understanding of particular merits and limitations. In particular, it is the intention to propose a minimum set of requirements a literature study should meet. Some international standards for measurements are already published, but modifications or revisions of such standards may be necessary for application to laser ablation propulsion. Issues relating to development of standards will be discussed, as well as some examples of specific experimental circumstances in which standardization would have prevented misinterpretation or misuse of past data.
Sinko, John E. [Micro-Nano Global Center of Excellence, Nagoya University (Niue), Nagoya, Aichi (Japan); Scharring, Stefan; Eckel, Hans-Albert [Institute of Technical Physics, German Aerospace Center (DLR), D-70569 Stuttgart, Pfaffenwaldring 38-40 (Germany); Roeser, Hans-Peter [Institute of Space Systems, University of Stuttgart, D-70569 Stuttgart, Pfaffenwaldring 31 (Germany); Sasoh, Akihiro [Department of Aerospace Engineering, Nagoya University, Nagoya, Aichi (Japan)
Numerical investigation of the thrust efficiency of a laser propelled vehicle
The flow situation for a thruster propelled by ablated gas which is energized by a laser pulse is numerically simulated. The flow is axisymmetric and nonsteady, and is assumed to be inviscid due to its high Reynolds number. The high pressure expansion of the laser heated gas generates thrust as it pushes against the vehicle. Gas expansion lateral to the thrust vector causes performance to decrease. The vehicle geometry and the laser pulse characteristics determine the degree to which the flow is one dimensional. As the thruster's parameters are varied, its impulse is calculated and compared to the limiting impulse of a one-dimensional system, and thus the thrust efficiency is computed. Lateral expansion losses computed by simulating the flow of the expanding gas time-accurately on a computer are far less than losses predicted using the method of characteristics, which is the best alternate means of computation. Flows which exhibit a substantial amount of lateral expansion can still yield an expansion efficiency which exceeds 70%. This finding has significant implications on the eventual design of flight hardware. Steger and Warming's flux split numerics for the Euler equations are modified for blast simulations into near vacuum ambient conditions. At the interface between the near vacuum ambient and the wave front, the solution is first order accurate but sufficiently robust to handle pressure ratios exceeding one million and density ratios exceeding 10,000 between the thrust gas and the ambient gas. Elsewhere the solution is second order accurate. The majority of the calculations performed assume an ideal gas equation of state with {gamma} = 1.2. The propellant Lithium Hydride has shown excellent promise in the laboratory, yielding I{sub sp} = 800-1000 sec. Equilibrium and kinetic modeling of LiH is undertaken, with a variable {gamma} of from 1.25 to 1.66 resulting from the kinetic assumptions of ionization equilibrium and frozen chemistry. These additional mechanisms are then incorporated into the efficiency calculations.
mulroy jr
Bubble Acceleration in the Ablative Rayleigh-Taylor Instability
The highly nonlinear evolution of the single-mode Rayleigh-Taylor instability (RTI) at the ablation front of an accelerated target is investigated in the parameter range typical of inertial confinement fusion implosions. A new phase of the nonlinear bubble evolution is discovered. After the linear growth phase and a short constant-velocity phase, it is found that the bubble is accelerated to velocities well above the classical value. This acceleration is driven by the vorticity accumulation inside the bubble resulting from the mass ablation and vorticity convection off the ablation front. While the ablative growth rates are slower than their classical values in the linear regime, the ablative RTI grows faster than the classical RTI in the nonlinear regime for deuterium and tritium ablators.
Betti, R.; Sanz, J. [Fusion Science Center for Extreme States of Matter and Fast Ignition Physics, Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)
Trace element fingerprinting of ancient Chinese gold with femtosecond laser
NLE Websites -- All DOE Office Websites (Extended Search)
Trace element fingerprinting of ancient Chinese gold with femtosecond laser Trace element fingerprinting of ancient Chinese gold with femtosecond laser ablation-inductivity coupled mass spectrometry Title Trace element fingerprinting of ancient Chinese gold with femtosecond laser ablation-inductivity coupled mass spectrometry Publication Type Journal Article Year of Publication 2009 Authors Brostoff, Lynn B., Jhanis J. Gonzalez, Paul Jett, and Richard E. Russo Journal Journal of Archeological Science Volume 36 Start Page 461 Issue 2 Pagination 461-466 Date Published 02/2009 Keywords Ancient gold, femtosecond, la-icp-ms, Trace element Abstract In this collaborative investigation, femtosecond laser ablation-inductively coupled mass spectrometry (LA-ICP-MS) was applied to the study of a remarkable group of ancient Chinese gold objects in the Smithsonian's Freer Gallery of Art and Arthur M. Sackler Gallery. Taking advantage of the superior ablation characteristics and high precision of a femtosecond 266 nm Ti:sapphire laser at Lawrence Berkeley National Laboratory, major, minor and trace element concentrations in the gold fragments were quantified. Results validate use of femtosecond LA-ICP-MS for revealing ''fingerprints'' in minute gold samples. These fingerprints allow us to establish patterns based on the association of silver, palladium and platinum that support historical, technical and stylistic relationships, and shed new light on these ancient objects.
Design of a deuterium and tritium-ablator shock ignition target for the National Ignition Facility
Shock ignition presents a viable path to ignition and high gain on the National Ignition Facility (NIF). In this paper, we describe the development of the 1D design of 0.5 MJ class, all-deuterium and tritium (fuel and ablator) shock ignition target that should be reasonably robust to Rayleigh-Taylor fluid instabilities, mistiming, and hot electron preheat. The target assumes 'day one' NIF hardware and produces a yield of 31 MJ with reasonable allowances for laser backscatter, absorption efficiency, and polar drive power variation. The energetics of polar drive laser absorption require a beam configuration with half of the NIF quads dedicated to launching the ignitor shock, while the remaining quads drive the target compression. Hydrodynamic scaling of the target suggests that gains of 75 and yields 70 MJ may be possible.
Terry, Matthew R.; Perkins, L. John; Sepke, Scott M. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States)
Casingless down-hole for sealing an ablation volume and obtaining a sample for analysis
A casing-less down hole sampling system for acquiring a subsurface sample for analysis using an inductively coupled plasma system is disclosed. The system includes a probe which is pushed into the formation to be analyzed using a hydraulic ram system. The probe includes a detachable tip member which has a soil point and a barb, with the soil point aiding the penetration of the earth, and the barb causing the tip member to disengage from the probe and remain in the formation when the probe is pulled up. The probe is forced into the formation to be tested, and then pulled up slightly, to disengage the tip member and expose a column of the subsurface formation to be tested. An instrumentation tube mounted in the probe is then extended outward from the probe to longitudinally extend into the exposed column. A balloon seal mounted on the end of the instrumentation tube allows the bottom of the column to be sealed. A source of laser radiation is emitted from the instrumentation tube to ablate a sample from the exposed column. The instrumentation tube can be rotated in the probe to sweep the laser source across the surface of the exposed column. An aerosol transport system carries the ablated sample from the probe to the surface for testing in an inductively coupled plasma system. By testing at various levels in the down-hole as the probe is extracted from the soil, a profile of the subsurface formation may be obtained. 9 figs.
Noble, D.T.; Braymen, S.D.; Anderson, M.S.
Casingless down-hole for sealing an ablation volume and obtaining a sample for analysis
A casing-less down hole sampling system for acquiring a subsurface sample for analysis using an inductively coupled plasma system is disclosed. The system includes a probe which is pushed into the formation to be analyzed using a hydraulic ram system. The probe includes a detachable tip member which has a soil point mad a barb, with the soil point aiding the penetration of the earth, and the barb causing the tip member to disengage from the probe and remain in the formation when the probe is pulled up. The probe is forced into the formation to be tested, and then pulled up slightly, to disengage the tip member and expose a column of the subsurface formation to be tested. An instrumentation tube mounted in the probe is then extended outward from the probe to longitudinally extend into the exposed column. A balloon seal mounted on the end of the instrumentation tube allows the bottom of the column to be sealed. A source of laser radiation is emitted from the instrumentation tube to ablate a sample from the exposed column. The instrumentation tube can be rotated in the probe to sweep the laser source across the surface of the exposed column. An aerosol transport system carries the ablated sample from the probe to the surface for testing in an inductively coupled plasma system. By testing at various levels in the down-hole as the probe is extracted from the soil, a profile of the subsurface formation may be obtained.
Noble, Donald T. (Ames, IA); Braymen, Steven D. (Ames, IA); Anderson, Marvin S. (Ames, IA)
Science Conference Proceedings (OSTI)
Kinetic Theory / Proceedings of the Ninth Carolus Magnus Summer School on Plasma and Fusion Energy Physics
B. Weyssow
Laser-material interactions: A study of laser energy coupling with solids
Science Conference Proceedings (OSTI)
This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heating of opaque solids that have not undergone phase-change. Of main interest is the physical significance of the shape, magnitude, and phase for the temporal profile of the deflection signal. Considered are the effects that thermophysical properties, boundary conditions, and geometry of the target and optical probe-beam have on the deflection response. PTD is shown to monitor spatial and temporal changes in heat flux leaving the surface due to changes in laser energy coupling. The PTD technique is then extended to detect phase-change at the surface of a solid target. Experimental data shows the onset of melt for indium and tin targets. The conditions for which melt can be detected by PTD is analyzed in terms of geometry, incident power and pulse length, and thermophysical properties of the target and surroundings. Next, monitoring high-powered laser ablation of materials with stress-power is introduced. The motivation for considering stress-power is given, followed by a theoretical discussion of stress-power and how it is determined experimentally. Experiments are presented for the ablation of aluminum targets as a function of energy and intensity. The stress-power response is analyzed for its physical significance. Lastly, the influence of plasma-shielding during high-powered pulsed laser-material interactions is considered. Crater size, emission, and stress-power are measured to determine the role that the gas medium and laser pulse length have on plasma shielding.
Shannon, M.A. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Mechanical Engineering
Plasmadynamics and ionization kinetics of thermionic energy conversion
To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)
Lawless, J.L. Jr.; Lam, S.H.
Bubble Acceleration in the Ablative Rayleigh-Taylor Instability
Science Conference Proceedings (OSTI)
The highly nonlinear evolution of the single-mode Rayleigh-Taylor instability (RTI) at the ablation front of an accelerated target is investigated in the parameter range typical of inertial confinement fusion implosions. A new phase of the nonlinear bubble evolution is discovered. After the linear growth phase and a short constant-velocity phase, it is found that the bubble is accelerated to velocities well above the classical value. This acceleration is driven by the vorticity accumulation inside the bubble resulting from the mass ablation adn vorticity convection off the ablation front. While the albative growth rates are slower than their classical values in the linear regime, the ablative RTI grows faster than the classical RTI in the nonlinear regime for deuterium and tritium ablators.
Betti, R.; Sanz, J.
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Ignition Laser Ignition A first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel...
Micro laser propulsion used for some space tasks of micro-satellites are preferred to providing small thrust and high specific impulse while keeping power consumption low. Most previous work on micro laser propulsion are about transmission mode (T-mode) using a CW laser. In this article, a pulsed fiber laser is used to study the micro laser propulsion performance under reflection mode. Multi pulse (ranged from 100 to 2000) tests are conducted on a double base propellant with the vacuum less than 10 Pa. The laser frequency is 20 kHz and two kinds of instantaneous power density 4.77x10{sup 6} W/cm{sup 2} and 2.39x10{sup 7} W/cm{sup 2} are used. It is found that the momentum coupling coefficient C{sub m} and the mean thrust F increases with the increasing pulse numbers, which is different to the previous work. By adjusting the irradiation time T, it is easy to get a large mean thrust, up to mN. When the energy density is the same, C{sub m}, I{sub sp}, F and {eta} increase with the increasing power density. Also I{sub sp} and {eta} are very low, laser ablation is insufficiently under the current condition. 3D Morphology of the ablation hole is obtained by confocal microscope for the first time.
Zhang Xinghua; Cai Jian [Microelectronic Equipment Technology Department, Institute of Microelectronics of the Chinese Academy of Sciences, Beijing, 100029 (China); Li Long [Department of Modern Mechanics, University of Science and Technology of China, Hefei, 230027 (China)
The effect of laser energy fluence on the onset and growth of Rayleigh-Taylor (RT) instabilities in laser induced Fe plasma is investigated using time-resolved fast gated imaging. The snow plow and shock wave models are fitted to the experimental results and used to estimate the ablation parameters and the density of gas atoms that interact with the ablated species. It is observed that RT instability develops during the interface deceleration stage and grows for a considerable time for higher laser energy fluence. The effects of RT instabilities formation on the surface topography of the Fe thin films grown in pulsed laser deposition system are investigated (i) using different laser energy fluences for the same wavelength of laser radiation and (ii) using different laser wavelengths keeping the energy fluence fixed. It is concluded that the deposition achieved under turbulent condition leads to less smooth deposition surfaces with bigger sized particle agglomerates or network.
Mahmood, S. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Department of Physics, University of Karachi, Karachi 75270 (Pakistan); Rawat, R. S.; Wang, Y.; Lee, S.; Tan, T. L.; Springham, S. V.; Lee, P. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Zakaullah, M. [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan)
Computational Thermodynamics and Kinetics
Science Conference Proceedings (OSTI)
Jul 31, 2011 ... About this Symposium. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium, Computational Thermodynamics and Kinetics.
Science Conference Proceedings (OSTI)
Basic and Kinetic Theory / Proceedings of the Tenth Carolus Magnus Summer School on Plasma and Fusion Energy Physics
B. Weyssow
of chemical reactions. · Only gases, for which the kinetic theory of Chapter 4 is applicable, are consideredChapter 13. Chemical Kinetics #12;· Why do some chemical reactions proceed with lighting speed when the way in which molecules combine to form products? · All of these questions involve chemical kinetics
Ihee, Hyotcherl
Femtosecond Laser Synthesis of Multi-Element Nanocrystals
We studied the conditions under which short-pulsed laser deposited (PLD) stoichiometric multi-element nanocrystals of GaAs,InP,CoPt and Inconel (an alloy of Cr, Fe and Ni) are formed. The properties of the PLD nanoclusters and the irradiated targets were investigated as a function of the laser pulse-length (150 fs-500 ps) and the inert background gas pressure in the synthesis chamber (microTorr to hundreds of Torr). Our results reveal that the formation of stoichiometric GaAs nanocrystals required ablating a GaAs target with a shorter than 25 ps laser in a {ge} 50 miliTorr of inert background pressure. For InP, a mixture of stoichiometric InP and In nanocrystals with an InP/In ratio of {approx} 1 resulted upon ablating an InP target in Ar at 1 Torr. This InP/In ratio increased to {approx} 5 when ablating the InP target in an Ar pressure of 750 Torr. In case of CoPt alloy, the stoichiometry in the target was not reflected in the collected nanocluster films, independent of the background gas pressure. Interestingly, the stoichiometry of the target was found in the collected nanocluster films when an Inconel target was ablated by a femtosecond laser even in vacuum. It is noted that the constituents of Inconel (Cr, Fe and Ni) have similar vapor pressures while Co and Pt do not. Our experimental results suggest that the stoichiometries of the PLD multi-element nanoclusters are closer with those of the targets when shorter than 25 ps lasers are used. However, this does not imply that simply irradiating a multi-element target in vacuum with a shorter than 25 ps pulse-length laser would automatically result in the formation of stoichiometric nanocrystals. The preservation of the stoichiometry of the irradiated target and the formation of stoichiometric semiconductor nanocrystals require ablating the targets with a shorter than 25 ps laser in a background gas. The minimum background gas pressure is materials dependent. And for metal alloys, the stoichiometry of the ablated target cannot be found in the collected nanocluster films if the constituent elements have widely different vapor pressures. We have also successfully used density-functional based tight-binding potentials to study the femtosecond laser/GaAs target interaction. This code work can be extended to other multi-element compounds/alloys as well.
Dinh, L N; Trelenberg, T; Torralva, B; Stuart, B C; Balooch, M
Ultrashort pulse high repetition rate laser system for biological tissue processing
A method and apparatus is disclosed for fast, efficient, precise and damage-free biological tissue removal using an ultrashort pulse duration laser system operating at high pulse repetition rates. The duration of each laser pulse is on the order of about 1 fs to less than 50 ps such that energy deposition is localized in a small depth and occurs before significant hydrodynamic motion and thermal conduction, leading to collateral damage, can take place. The depth of material removed per pulse is on the order of about 1 micrometer, and the minimal thermal and mechanical effects associated with this ablation method allows for high repetition rate operation, in the region 10 to over 1000 Hertz, which, in turn, achieves high material removal rates. The input laser energy per ablated volume of tissue is small, and the energy density required to ablate material decreases with decreasing pulse width. The ablation threshold and ablation rate are only weakly dependent on tissue type and condition, allowing for maximum flexibility of use in various biological tissue removal applications. The use of a chirped-pulse amplified Titanium-doped sapphire laser is disclosed as the source in one embodiment.
Neev, Joseph (Laguna Beach, CA); Da Silva, Luiz B. (Danville, CA); Matthews, Dennis L. (Moss Beach, CA); Glinsky, Michael E. (Livermore, CA); Stuart, Brent C. (Fremont, CA); Perry, Michael D. (Livermore, CA); Feit, Michael D. (Livermore, CA); Rubenchik, Alexander M. (Livermore, CA)
Spectroscopy, Kinetics, and Dynamics of Combustion Radicals
Spectroscopy, kinetics and dynamics of jet cooled hydrocarbon transients relevant to the DOE combustion mission have been explored, exploiting i) high resolution IR lasers, ii) slit discharge sources for formation of jet cooled radicals, and iii) high sensitivity detection with direct laser absorption methods and near the quantum shot noise limit. What makes this combination powerful is that such transients can be made under high concentrations and pressures characteristic of actual combustion conditions, and yet with the resulting species rapidly cooled (T ?10-15K) in the slit supersonic expansion. Combined with the power of IR laser absorption methods, this provides novel access to spectral detection and study of many critical combustion species.
Nesbitt, David J. [Research/Professor
Development of pulse laser processing for mounting fiber Bragg grating
Pulse laser processing has been developed for the application of industrial plants in monitoring and maintenance. Surface cleaning by nano-second laser ablation was demonstrated for decontamination of oxide layers of Cr contained steel. Direct writing by femtosecond processing induced a Bragg grating in optical fiber to make it a seismic sensor for structural health monitoring. Adhesive cement was used to fix the seismic sensor on the surface of reactor coolant pipe material. Pulse laser processing and its related technologies were presented to overcome the severe accidents of nuclear power plants.
Nishimura, Aikihko; Shimada, Yukihiro; Yonemoto, Yukihiro; Suzuki, Hirokazu; Ishibashi, Hisayoshi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umebidai Kidugawa Kyoto 619-0215 (Japan); Applied Laser Technology Institute, Tsuruga Head Office, Japan Atomic Energy Agency, 65-20 Kizaki Tsuruga Fukui 914-8585 (Japan); Technical Research and Development Institute, Kumagai Gumi Co., Ltd., 2-1 Tsukudo, Shinjuku Tokyo 162-8557 (Japan)
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Laser Ignition Laser Ignition Laser Ignition A first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Available for thumbnail of Feynman Center (505) 665-9090 Email Laser Ignition A first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In two embodiments the beam from the excitation light source is split with a portion of it going to the ignitor laser and a second portion
Composition analysis by scanning femtosecond laser ultraprobing (CASFLU).
The composition analysis by scanning femtosecond ultraprobing (CASFLU) technology scans a focused train of extremely short-duration, very intense laser pulses across a sample. The partially-ionized plasma ablated by each pulse is spectrometrically analyzed in real time, determining the ablated material's composition. The steering of the scanned beam thus is computer directed to either continue ablative material-removal at the same site or to successively remove nearby material for the same type of composition analysis. This invention has utility in high-speed chemical-elemental, molecular-fragment and isotopic analyses of the microstructure composition of complex objects, e.g., the oxygen isotopic compositions of large populations of single osteons in bone.
Ishikawa, Muriel Y. (Livermore, CA); Wood, Lowell L. (Simi Valley, CA); Campbell, E. Michael (Danveille, CA); Stuart, Brent C. (Livermore, CA); Perry, Michael D. (Livermore, CA)
Computational Thermodynamics and Kinetics
Science Conference Proceedings (OSTI)
A Comprehensive Investigation of Low Angle Grain Boundary Mobility in Pure Al ... A New Treatment for the Kinetics of Isothermal Oxidation of Zinc Powders.
Science Conference Proceedings (OSTI)
Mar 4, 2013 ... Materials Science in Reduced Gravity: Structure and Kinetics ... Bias fields comprise weak interface energy sources that result from the vector�...
Dependence of terahertz power from laser-produced plasma on laser intensity
Power of terahertz radiation from plasma which is generated from air irradiated by coupled ({omega}, 2{omega}) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.
Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Photon Pioneers Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka (Japan)
Science Conference Proceedings (OSTI)
... over a wide range of powers, energies, and wavelengths. ... the SI units for laser power and energy. ... Novel power meter for high-efficiency laser diode ...
Picosecond laser structuring of thin film platinum layers covered with tantalum pentoxide isolation
Science Conference Proceedings (OSTI)
A thin film layer system consisting of platinum (Pt) as conductive layer on a glass substrate and tantalum pentoxide as isolating layer on top of the platinum is attractive for designing biocompatible conductor paths and contact pads for bio sensor chips. For the flexible and rapid patterning of the conductive and the isolating layers, both, the complete removal and the selective ablation of the individual thin films were investigated using ultra-short laser pulses with about 10 ps pulse duration and 1064 nm wavelength at low laser fluences. A platinum film covered with tantalum pentoxide shows a significantly lower ablation threshold than a single Pt film on glass alone when illuminated from the front side. Furthermore, we explored that the tantalum pentoxide film can be removed by glass side illumination from the Pt film, without affecting the Pt film and leaving the Pt film on the glass substrate intact. Those ablation phenomena occur at laser fluences of about 0.2 J/cm{sup 2}, far below the evaporation limit of platinum. We present a detailed ablation threshold value examination for the structuring of these layer systems by front side and glass side irradiation for different film thicknesses. Furthermore, we discuss the possible underlying physical mechanisms of these ablation phenomena.
Heise, Gerhard; Huber, Heinz [Lasercenter, Munich University of Applied Sciences, Lothstr. 34, D-80335 Muenchen (Germany); Trappendreher, Daniel [Heinz-Nixdorf-Chair for Medical Electronics, Technische Universitaet Muenchen, Theresienstrasse 90, D-80333 Muenchen (Germany); Lasercenter, Munich University of Applied Sciences, Lothstr. 34, D-80335 Muenchen (Germany); Ilchmann, Florian; Weiss, Robin S.; Wolf, Bernhard [Heinz-Nixdorf-Chair for Medical Electronics, Technische Universitaet Muenchen, Theresienstrasse 90, D-80333 Muenchen (Germany)
Epitaxial growth of metal fluoride thin films by pulsed-laser deposition
We have studied growth of GdLiF4 thin films for optical waveguide applications. Epitaxial, c-axis oriented GdLiF4 films wer grown from undoped GdLiF4 targets in an on-axis Pulsed-laser deposition geometry on (100) CaF2. These films exhibit a high density of particulates on the surface which are ejected from the target in the ablation process. Growth from Nd-doped polycrystalline GdLiF4 ablation targets results in smooth films with lower particulate densities, as Nd doping increases the optical absorption of GdLiF4 at the ablation laser wavelength 193 nm and permits efficient pulsed-laser deposition. Optical emission spectra of the ablation pume reveals the presence of atomic F, Gd, and Li, indicating the dissociation of the metal-fluorine bonds in the ablation process. In addition, we find that the residual background oxygen pressure must be reduced to avoid formation of Gd4O3F6 as an impurity oxyfluoride phase in the films.
Norton, D.P.; Budal, J.D.; Chakoumakos, B.C.; Geohegan, D.B. [Oak Ridge National Lab., TN (United States); Puretzky, A. [AN SSSR, Troitsk (Russian Federation). Inst. Spektroskopii
A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.
Gruen, Dieter M. (Downers Grove, IL)
Laser Fine-Adjustment Thruster For Space Vehicles
To the present time, a few laser propulsion engine devices have been developed by using dominant mechanisms of laser propulsion. Generally these mechanisms are laser ablation, laser breakdown of gases, and laser detonation waves that are induced due to extraction of the internal energy of polymer propellants. In the paper, we consider the Aero-Space Laser Propulsion Engine (ASLPE) developed earlier, in which all of these mechanisms are realized via interaction of laser radiation with polymers both in continuous wave (CW) and in repetitively pulsed modes of laser operation. The ASLPE is considered to be exploited as a unit of a laser propulsion device being arranged onboard space vehicles moving around the Earth or in interplanetary missions and intended to correct the vehicles orbits. To produce a thrust, a power of the solar pumped lasers designed to the present time is considered in the paper. The problem of increasing the efficiency of the laser propulsion device is analyzed as applied to space missions of vehicles by optimizing the laser propulsion propellant composition.
Rezunkov, Yu. A.; Egorov, M. S.; Repina, E. V.; Safronov, A. L. [Research Institute for Complex Testing of Optic-Electronic Devices, Sosnovy Bor, Leningrad region, Russian Federation, 188540 (Russian Federation); Rebrov, S. G. [Keldyish Research Center, Moscow (Russian Federation)
High Energy Laser for Space Debris Removal
The National Ignition Facility (NIF) and Photon Science Directorate at Lawrence Livermore National Laboratory (LLNL) has substantial relevant experience in the construction of high energy lasers, and more recently in the development of advanced high average power solid state lasers. We are currently developing new concepts for advanced solid state laser drivers for the Laser Inertial Fusion Energy (LIFE) application, and other high average power laser applications that could become central technologies for use in space debris removal. The debris population most readily addressed by our laser technology is that of 0.1-10 cm sized debris in low earth orbit (LEO). In this application, a ground based laser system would engage an orbiting target and slow it down by ablating material from its surface which leads to reentry into the atmosphere, as proposed by NASA's ORION Project. The ORION concept of operations (CONOPS) is also described in general terms by Phipps. Key aspects of this approach include the need for high irradiance on target, 10{sup 8} to 10{sup 9} W/cm{sup 2}, which favors short (i.e., picoseconds to nanoseconds) laser pulse durations and high energy per pulse ({approx} > 10 kJ). Due to the target's orbital velocity, the potential duration of engagement is only of order 100 seconds, so a high pulse repetition rate is also essential. The laser technology needed for this application did not exist when ORION was first proposed, but today, a unique combination of emerging technologies could create a path to enable deployment in the near future. Our concepts for the laser system architecture are an extension of what was developed for the National Ignition Facility (NIF), combined with high repetition rate laser technology developed for Inertial Fusion Energy (IFE), and heat capacity laser technology developed for military applications. The 'front-end' seed pulse generator would be fiber-optics based, and would generate a temporally, and spectrally tailored pulse designed for high transmission through the atmosphere, as well as efficient ablative coupling to the target. The main amplifier would use either diode-pumped or flashlamp-pumped solid state gain media, depending on budget constraints of the project. A continuously operating system would use the gas-cooled amplifier technology developed for Mercury, while a burst-mode option would use the heat capacity laser technology. The ground-based system that we propose is capable of rapid engagement of targets whose orbits cross over the site, with potential for kill on a single pass. Very little target mass is ablated per pulse so the potential to create additional hazardous orbiting debris is minimal. Our cost estimates range from $2500 to $5000 per J depending on choices for laser gain medium, amplifier pump source, and thermal management method. A flashlamp-pumped, Nd:glass heat-capacity laser operating in the burst mode would have costs at the lower end of this spectrum and would suffice to demonstrate the efficacy of this approach as a prototype system. A diode-pumped, gas-cooled laser would have higher costs but could be operated continuously, and might be desirable for more demanding mission needs. Maneuverability can be incorporated in the system design if the additional cost is deemed acceptable. The laser system would need to be coupled with a target pointing and tracking telescope with guide-star-like wavefront correction capability.
Barty, C; Caird, J; Erlandson, A; Beach, R; Rubenchik, A
High Energy Laser for Space Debris Removal
The National Ignition Facility (NIF) and Photon Science Directorate at Lawrence Livermore National Laboratory (LLNL) has substantial relevant experience in the construction of high energy lasers, and more recently in the development of advanced high average power solid state lasers. We are currently developing new concepts for advanced solid state laser drivers for the Laser Inertial Fusion Energy (LIFE) application, and other high average power laser applications that could become central technologies for use in space debris removal. The debris population most readily addressed by our laser technology is that of 0.1-10 cm sized debris in low earth orbit (LEO). In this application, a ground based laser system would engage an orbiting target and slow it down by ablating material from its surface which leads to reentry into the atmosphere, as proposed by NASA's ORION Project. The ORION concept of operations (CONOPS) is also described in general terms by Phipps. Key aspects of this approach include the need for high irradiance on target, 10{sup 8} to 10{sup 9} W/cm{sup 2}, which favors short (i.e., picoseconds to nanoseconds) laser pulse durations and high energy per pulse ({approx} > 10 kJ). Due to the target's orbital velocity, the potential duration of engagement is only of order 100 seconds, so a high pulse repetition rate is also essential. The laser technology needed for this application did not exist when ORION was first proposed, but today, a unique combination of emerging technologies could create a path to enable deployment in the near future. Our concepts for the laser system architecture are an extension of what was developed for the National Ignition Facility (NIF), combined with high repetition rate laser technology developed for Inertial Fusion Energy (IFE), and heat capacity laser technology developed for military applications. The 'front-end' seed pulse generator would be fiber-optics based, and would generate a temporally, and spectrally tailored pulse designed for high transmission through the atmosphere, as well as efficient ablative coupling to the target. The main amplifier would use either diode-pumped or flashlamp-pumped solid state gain media, depending on budget constraints of the project. A continuously operating system would use the gas-cooled amplifier technology developed for Mercury, while a burst-mode option would use the heat capacity laser technology. The ground-based system that we propose is capable of rapid engagement of targets whose orbits cross over the site, with potential for kill on a single pass. Very little target mass is ablated per pulse so the potential to create additional hazardous orbiting debris is minimal. Our cost estimates range from $2500 to $5000 per J depending on choices for laser gain medium, amplifier pump source, and thermal management method. A flashlamp-pumped, Nd:glass heat-capacity laser operating in the burst mode would have costs at the lower end of this spectrum and would suffice to demonstrate the efficacy of this approach as a prototype system. A diode-pumped, gas-cooled laser would have higher costs but could be operated continuously, and might be desirable for more demanding mission needs. Maneuverability can be incorporated in the system design if the additional cost is deemed acceptable. The laser system would need to be coupled with a target pointing and tracking telescope with guide-star-like wavefront correction capability.
Barty, C; Caird, J; Erlandson, A; Beach, R; Rubenchik, A
Picosecond laser structuration under high pressures: Observation of boron nitride nanorods
We report on picosecond UV-laser processing of hexagonal boron nitride (BN) at moderately high pressures above 500 bar. The main effect is specific to the ambient gas and laser pulse duration in the ablation regime: when samples are irradiated by 5 or 0.45 ps laser pulses in nitrogen gas environment, multiple nucleation of a new crystalline product-BN nanorods-takes place. This process is triggered on structural defects, which number density strongly decreases upon recrystallization. Nonlinear photon absorption by adsorbed nitrogen molecules is suggested to mediate the nucleation growth. High pressure is responsible for the confinement and strong backscattering of ablation products. A strong surface structuring also appears at longer 150 ps laser irradiation in similar experimental conditions. However, the transformed product in this case is amorphous strongly contaminated by boron suboxides B{sub x}O{sub y}.
Museur, Luc [Laboratoire de Physique des Lasers-LPL CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Petitet, Jean-Pierre; Kanaev, Andrei V. [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions-LIMHP CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Michel, Jean-Pierre [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions-LIMHP CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Laboratoire des Proprietes Mecaniques et Thermodynamiques des Materiaux-LPMTM CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Marine, Wladimir [Centre Interdisciplinaire de Nanoscience de Marseille-CINaM, UPR CNRS 3118, Faculte des Science de Luminy, 13288 Marseille (France); Anglos, Demetrios [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), 71110 Heraklion, Crete (Greece); Fotakis, Costas [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), 71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, Heraklion, Crete (Greece)
A Pulsed Laser-Electromagnetic Hybrid Accelerator For Space Propulsion Application
A fundamental study of a newly developed rectangular pulsed laser-electromagnetic hybrid thruster was conducted, in which laser-ablation plasma was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. The performance of the thruster was evaluated by measuring the mass per shot and impulse bit. As results, significantly high specific impulse ranging from 5,000 approx6,000 sec were obtained at energies of 0.1 and 8.6 J, respectively. In addition, the typical thrust efficiency varied from 17% to 19% depending on the charge energy.
Shinohara, Tadaki; Horisawa, Hideyuki [Department of Aeronautics and Astronautics, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292 Japan (Japan); Baba, Msahumi; Tei, Kazuyoku [Department of Physics, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan)
Ultrafast electron beam imaging of femtosecond laser-induced plasma
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Ultrafast electron beam imaging of femtosecond laser-induced plasma Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Title Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Publication Type Journal Article Year of Publication 2010 Authors Li, Junjie, Xuan Wang, Zhaoyang Chen, Richard Clinite, Samuel S. Mao, Pengfei Zhu, Zhengming Sheng, Jie Zhang, and Jianming Cao Journal Journal of Applied Physics Volume 107 Issue 8 Date Published 03/2010 Keywords copper, electron beam applications, high-speed optical techniques, laser ablation, plasma diagnostics, plasma production by laser Abstract Plasma dynamics in the early stage of laser ablation of a copper target are investigated in real time by making ultrafast electron shadow images and electron deflectometry measurements. These complementary techniques provide both a global view and a local perspective of the associated transient electric field and charge expansion dynamics. The results reveal that the charge cloud above the target surface is composed predominantly of thermally ejected electrons and that it is self-expanding, with a fast front-layer speed exceeding 107 m/s. The average electric field strength of the charge cloud induced by a pump fluence of 2.2 J/cm2 is estimated to be ∼ 2.4×105 V/m.
Nonlinear Theory of the Ablative Rayleigh-Taylor Instability
Here, a model for the nonlinear Rayleigh-Talyor instability (RTI) of a steady ablation front based on a sharp boundary approximation is presented. The model includes the effect of mass ablation and represents a basic tool for investigating many aspects of the nonlinear ablative RTI relevant to inertial confinement fusion. The single mode analysis shows the development of a nonlinear exponential instability for wave numbers close to the linear cutoff. Such a nonlinear instability grows at a rate faster than the linear growth rate and leads to saturation amplitudes significantly larger than the classical value 0.1 lambda. We also found that linearly stable perturbations with wave numbers larger than the linear cutoff become unstable when their initial amplitudes exceed a threshold vlaue. The shedding of long wavelength modes via mode coupling is much greater than predicted by the classical RTI theory. The effects of ablation on the evolution of a front of bubbles is also investigated and the front acceleration is computed.
Sanz, J.; Betti, R.; Ramis, R.; Ramirez, J.
Thermodynamic and Kinetic Modeling
Science Conference Proceedings (OSTI)
Oct 11, 2012... capability of the coating and thus the achievable engine efficiency. ... Aluminide coating of steels enables more efficient power generation through ... and kinetic modeling in order to build a time and temperature dependent�...
Thermodynamic & Kinetic Data for Sustainable Energy
Science Conference Proceedings (OSTI)
Thermodynamic & Kinetic Data for Sustainable Energy. Summary: Industry needs thermodynamic and kinetic data for the ...
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mNAL PERFORMANCE REPORT mNAL PERFORMANCE REPORT for INFRARED ABSORPTION SPECTROSCOPY AND CHEMICAL KINETICS OF FREE RADICALS DE-FG05-85ER13439 1-AUG-1985 to 31-JUL-1994 Robert F. Curl and Graham P. Glass Principal Investigators Introduction This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then
Science Conference Proceedings (OSTI)
For more information about my work on laser spectroscopy, consult the following papers: Sansonetti, CJ, Gillaspy, JD, and ...
Inertial fusion with ultra-powerful lasers
Ultra-high intensity lasers can be used to ignite ICF capsules with a few tens of kilojoules of light and can lead to high gain with as little as 100 kilojoules of incident laser light. We propose a scheme with three phases. First, a capsule is imploded as in the conventional approach to inertial fusion to assemble a high density fuel configuration. Second, a hole is bored through capsule corona composed of ablated material, pushing critical density close to the high density core of the capsule, by employing the ponderomotive force associated with high intensity laser light. Finally, the fuel is ignited by suprathermal electrons, produced in the high intensity laser plasma interactions, which propagate from critical density to this high density core. This paper reviews two models of energy gain in ICF capsules and explains why ultra-high intensity lasers allow access to the model producing the higher gains. This new scheme also drastically reduces the difficulty of the implosion and thereby allows lower quality fabrication and less stringent beam quality and symmetry requirements from the implosion driver. The difficulty of the fusion scheme is transferred to the technological difficulty of producing the ultra-high-intensity laser and of transporting this energy to the fuel.
Tabak, M.; Hammer, J.; Glinsky, M.; Kruer, W.; Wilks, S.; Woodworth, J.; Campbell, E.M.; Perry, M.D.; Mason, R.
Evolution of ultrashort laser pulse in large amplitude plasma waves
Science Conference Proceedings (OSTI)
The propagation and evolution of an ultrashort laser pulse in a large amplitude plasma wave are investigated based on the photon kinetic theory. The photon number distribution function for a laser pulse in the phase space is analytically obtained by solving the photon kinetic equation in the background plasma wave. And then, the behavior of the laser pulse can be described by combining the single photon dynamics and the photon number distribution function. The evolutions of the photon number density in the coordinate and frequency domain space are discussed, and broadening or compressing of the laser pulse is also displayed in this paper. In particular, the frequency shift of the entire laser pulse is analyzed, which reflects a way of energy transformation between the laser pulse and the plasma wave.
Bu Zhigang [Department of Physics, Shanghai University, Shanghai 200444 (China); Ji Peiyong [Department of Physics, Shanghai University, Shanghai 200444 (China); The Shanghai Key Lab of Astrophysics, Shanghai 200234 (China)
A new laser concept is presented, called the athermal laser, unifying all the hitherto known implementations of radiative laser cooling.
Muys, Peter
Erbium hydride decomposition kinetics.
Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.
Ferrizz, Robert Matthew
A laser device includes a target position, an optical component separated a distance J from the target position, and a laser energy source separated a distance H from the optical component, distance H being greater than distance J. A laser source manipulation mechanism exhibits a mechanical resolution of positioning the laser source. The mechanical resolution is less than a spatial resolution of laser energy at the target position as directed through the optical component. A vertical and a lateral index that intersect at an origin can be defined for the optical component. The manipulation mechanism can auto align laser aim through the origin during laser source motion. The laser source manipulation mechanism can include a mechanical index. The mechanical index can include a pivot point for laser source lateral motion and a reference point for laser source vertical motion. The target position can be located within an adverse environment including at least one of a high magnetic field, a vacuum system, a high pressure system, and a hazardous zone. The laser source and an electro-mechanical part of the manipulation mechanism can be located outside the adverse environment. The manipulation mechanism can include a Peaucellier linkage.
Scott, Jill R. (Idaho Falls, ID); Tremblay, Paul L. (Idaho Falls, ID)
Direct evidence of mismatching effect on H emission in laser-induced atmospheric helium gas plasma
Science Conference Proceedings (OSTI)
A time-resolved orthogonal double pulse laser-induced breakdown spectroscopy (LIBS) with helium surrounding gas is developed for the explicit demonstration of time mismatch between the passage of fast moving impurity hydrogen atoms and the formation of thermal shock wave plasma generated by the relatively slow moving major host atoms of much greater masses ablated from the same sample. Although this so-called 'mismatching effect' has been consistently shown to be responsible for the gas pressure induced intensity diminution of hydrogen emission in a number of LIBS measurements using different ambient gases, its explicit demonstration has yet to be reported. The previously reported helium assisted excitation process has made possible the use of surrounding helium gas in our experimental set-up for showing that the ablated hydrogen atoms indeed move faster than the simultaneously ablated much heavier major host atoms as signaled by the earlier H emission in the helium plasma generated by a separate laser prior to the laser ablation. This conclusion is further substantiated by the observed dominant distribution of H atoms in the forward cone-shaped target plasma.
Zener Sukra Lie; Koo Hendrik Kurniawan [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); May On Tjia [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia); Rinda, Hedwig [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang Selatan 15314, Banten (Indonesia); Syahrun Nur Abdulmadjid; Nasrullah Idris [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Alion Mangasi Marpaung [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, Rawamangun, Jakarta 12440 (Indonesia); Marincan Pardede [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Muliadi Ramli [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Heri Suyanto [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Fukumoto, Kenichi; Kagawa, Kiichiro [Research Institute of Nuclear Engineering, University of Fukui, Fukui 910-8507 (Japan)
Science Conference Proceedings (OSTI)
Tetracycline is an antibiotic that absorbs ultraviolet light at 355 nm and preferentially binds to atherosclerotic plaque both in vitro and in vivo. Tetracycline-treated human cadaveric aorta was compared with untreated aorta using several techniques: absorptive spectrophotometry; and tissue uptake of radiolabeled tetracycline, which showed 4-fold greater uptake by atheroma than by normal vessel. In addition, intravenous tetracycline administered to patients undergoing vascular surgery demonstrated characteristic fluorescence in surgically excised diseased arteries. Because of tetracycline's unique properties, the authors exposed tetracycline-treated and untreated aorta to ultraviolet laser radiation at a wavelength of 355 nm. They found enhanced ablation of tetracycline-treated atheroma compared with untreated atheroma. The plaque ablation caused by ultraviolet laser radiation was twice as extensive in tetracycline-treated vs nontreated plaque. This study demonstrates the potential of tetracycline plaque enhancement for the selective destruction of atheroma by ultraviolet laser radiation.
Murphy-Chutorian, D.; Kosek, J.; Mok, W.; Quay, S.; Huestis, W.; Mehigan, J.; Profitt, D.; Ginsburg, R.
Science Conference Proceedings (OSTI)
The microstructural impact of selective femtosecond laser ablation of thin dielectric layers from monocrystalline silicon wafers was investigated. Various spots opened by 280 fs laser pulses at {lambda} = 1.03 {mu}m wavelength and 50 fs pulses at 800 nm, respectively, were analyzed in detail using Raman and transmission electron microscopy. The results show clearly that the thin dielectric films can be removed without any detectable modification of the Si crystal structure in the opened area. In contrast, in adjacent regions corresponding to laser fluence slightly below the breaking threshold, a thin layer of amorphous silicon with a maximum thickness of about 50 nm is found at the Si/SiO{sub 2} interface after laser irradiation. More than one pulse on the same position, however, causes structural modification of the silicon after thin film ablation in any case.
Rublack, Tino; Muchow, Markus [Zentrum fuer Innovationskompetenz SiLi-nano, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany); Schade, Martin; Leipner, Hartmut S. [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet Halle-Wittenberg, 06099 Halle (Germany); Seifert, Gerhard [Zentrum fuer Innovationskompetenz SiLi-nano, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany); Fraunhofer-Center for Silicon Photovoltaics CSP, 06120 Halle (Germany)
Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-ray Preheat
To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, <<10{sup 13} W/cm{sup 2}, compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flashcoating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe.
Colvin, J D; Kalantar, D H
Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.
Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J
Technology assessment of laser-fusion power production
The inherent features of laser-induced fusion, some laser-fusion reactor concepts, and attendant means of utilizing the thermonuclear energy for commercial electric power generation are discussed. Theoretical fusion-pellet microexplosion energy release characteristics are described and the effects of pellet design options on pellet-microexplosion characteristics are discussed. The results of analyses to assess the engineering feasibility of reactor cavities for which protection of cavity components is provided either by suitable ablative materials or by diversion of plasmas by magnetic fields are presented. Two conceptual laser-fusion electric generating stations, based on different laser-fusion reactor concepts, are described. Technology developments for ultimate commercial application are outlined.
Booth, L.A.; Frank, T.G.
LLNL Chemical Kinetics Modeling Group
The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.
Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J
Kinetic Theory of Plasma Waves
Science Conference Proceedings (OSTI)
Kinetic Wave Theory / Proceedings of the Tenth Carolus Magnus Summer School on Plasma and Fusion Energy Physics
D. Van Eester; E. Lerche
Kinetic equilibrium and relativistic thermodynamics
Relativistic thermodynamics is treated from the point of view of kinetic theory. It is shown that the generalized J\\"uttner distribution suggested in [1] is compatible with kinetic equilibrium. The requirement of compatibility of kinetic and thermodynamic equilibrium reveals several generalizations of the Gibbs relation where the velocity field is an independent thermodynamic variable.
P. V�n
Kinetic equilibrium and relativistic thermodynamics
Relativistic thermodynamics is treated from the point of view of kinetic theory. It is shown that the generalized J\\"uttner distribution suggested in [1] is compatible with kinetic equilibrium. The requirement of compatibility of kinetic and thermodynamic equilibrium reveals several generalizations of the Gibbs relation where the velocity field is an independent thermodynamic variable.
V�n, P
NIST Laser Applications Group Homepage
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Laser Applications Group. Welcome. The Laser Applications Group advances laser technology for applications in optical ...
Science Conference Proceedings (OSTI)
...Several models of metalworking lasers of both domestic and foreign manufacture are commercially available. The majority of these are of either the neodymium yttrium-aluminum garnet (Nd:YAG) solid-state type or the carbon dioxide (CO 2 ) gas type. These lasers may have pulsed or...
A laser device includes a virtual source configured to aim laser energy that originates from a true source. The virtual source has a vertical rotational axis during vertical motion of the virtual source and the vertical axis passes through an exit point from which the laser energy emanates independent of virtual source position. The emanating laser energy is collinear with an orientation line. The laser device includes a virtual source manipulation mechanism that positions the virtual source. The manipulation mechanism has a center of lateral pivot approximately coincident with a lateral index and a center of vertical pivot approximately coincident with a vertical index. The vertical index and lateral index intersect at an index origin. The virtual source and manipulation mechanism auto align the orientation line through the index origin during virtual source motion.
Scott, Jill R. (Idaho Falls, ID); Tremblay, Paul L. (Idaho Falls, ID)
Accurate guidance of an ablation catheter is critical in the RF ablation (RFA) of ventricular tachycardia (VT). With current technologies, it is challenging to rapidly and accurately localize the site of origin of an ...
Hirschman, Gordon B.
Science Conference Proceedings (OSTI)
Ejecta knot flickering, ablation tails, and fragmentation are expected signatures associated with the gradual dissolution of high-velocity supernova (SN) ejecta caused by their passage through an inhomogeneous circumstellar medium or interstellar medium (ISM). Such phenomena mark the initial stages of the gradual merger of SN ejecta with and the enrichment of the surrounding ISM. Here we report on an investigation of this process through changes in the optical flux and morphology of several high-velocity ejecta knots located in the outskirts of the young core-collapse SN remnant Cassiopeia A using Hubble Space Telescope images. Examination of WFPC2 F675W and combined ACS F625W + F775W images taken between 1999 June and 2004 December of several dozen debris fragments in the remnant's northeast ejecta stream and along the remnant's eastern limb reveal substantial emission variations ('flickering') over timescales as short as nine months. Such widespread and rapid variability indicates knot scale lengths {approx_equal} 10{sup 15} cm and a highly inhomogeneous surrounding medium. We also identify a small percentage of ejecta knots located all around the remnant's outer periphery which show trailing emissions typically 0.''2-0.''7 in length aligned along the knot's direction of motion suggestive of knot ablation tails. We discuss the nature of these trailing emissions as they pertain to ablation cooling, knot disruption, and fragmentation, and draw comparisons to the emission 'strings' seen in {eta} Car. Finally, we identify several tight clusters of small ejecta knots which resemble models of shock-induced fragmentation of larger SN ejecta knots caused by a high-velocity interaction with a lower density ambient medium.
Fesen, Robert A.; Zastrow, Jordan A.; Hammell, Molly C. [6127 Wilder Laboratory, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Shull, J. Michael; Silvia, Devin W. [CASA, Department of Astrophysical and Planetary Science, University of Colorado, Boulder, CO 80309 (United States)
Palliative Treatment of Rectal Carcinoma Recurrence Using Radiofrequency Ablation
Science Conference Proceedings (OSTI)
Purpose: To evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation for the palliative treatment of recurrent unresectable rectal tumors. Materials and Methods: Twenty-seven patients with locally recurrent rectal cancer were treated with computed tomography (CT)-guided RF ablation. Therapy was performed with the patient under conscious sedation with a seven- or a nine-array expandable RF electrode for 8-10 min at 80-110 Degree-Sign C and a power of 90-110 W. All patients went home under instructions the next day of the procedure. Brief Pain Inventory score was calculated before and after (1 day, 1 week, 1 month, 3 months, and 6 months) treatment. Results: Complete tumor necrosis rate was 77.8% (21 of a total 27 procedures) despite lesion location. BPI score was dramatically decreased after the procedure. The mean preprocedure BPI score was 6.59, which decreased to 3.15, 1.15, and 0.11 at postprocedure day 1, week 1, and month 1, respectively, after the procedure. This decrease was significant (p < 0.01 for the first day and p < 0.001 for the rest of the follow-up intervals (paired Student t test; n - 1 = 26) for all periods during follow-up. Six patients had partial tumor necrosis, and we were attempted to them with a second procedure. Although the necrosis area showed a radiographic increase, no complete necrosis was achieved (secondary success rate 65.6%). No immediate or delayed complications were observed. Conclusion: CT-guided RF ablation is a minimally invasive, safe, and highly effective technique for treatment of malignant rectal recurrence. The method is well tolerated by patients, and pain relief is quickly achieved.
Mylona, Sophia, E-mail: email@example.com; Karagiannis, Georgios, E-mail: firstname.lastname@example.com; Patsoura, Sofia, E-mail: firstname.lastname@example.com [Hellenic Red Cross Hospital 'Korgialenio-Benakio' (Greece); Galani, Panagiota, E-mail: firstname.lastname@example.com [Amalia Fleming Hospital (Greece); Pomoni, Maria, E-mail: email@example.com [Evgenidion Hospital (Greece); Thanos, Loukas, E-mail: firstname.lastname@example.com [Sotiria Hospital (Greece)
Science Conference Proceedings (OSTI)
This work presents an evaluation of a novel augmented reality approach for the visualisation of real time guidance of an ablation tool to a tumor in open liver surgery. The approach uses a portable image overlay device, directly integrated into a liver ... Keywords: ablation, augmented reality, image guidance, metastatic liver cancer, projection
Kate Alicia Gavaghan; Sylvain Anderegg; Matthias Peterhans; Thiago Oliveira-Santos; Stefan Weber
IDetachable, Human-Rated, Ablative Environmentally Compliant TPSLunar Surface Systems 2008 Phase II
Systems 2008 Phase II Proposal X8.01-8631 Lightweight Hybrid Ablator Incorporating Aerogel-Filled Open skeleton filled with a high temperature nanoscale aerogel insulator. Structural integrity and high insulation behavior have been demonstrated when used in combination with a non-ablating, coated carbon
� Community needs to work together to provide the technical case for funding an IFE program. � IFE program should nurture competition, with judgments made on the basis of technical progress and the potential of the various approaches to IFE. � Direct-drive with lasers looks very attractive for IFE, the physics and needed technologies are mature and advancing. � KrF provides physics advantages for direct drive. � KrF�s demonstrated performance is competitive with solid state lasers as a high-rep-rate durable, efficient IFE driver. (on several important parameters KrF technology leads) Direct Laser Drive is a better choice for Energy
Steve Obenschain
According to the invention, the gas laser comprises a housing which accommodates two electrodes. One of the electrodes is sectional and has a ballast resistor connected to each section. One of the electrodes is so secured in the housing that it is possible to vary the spacing between the electrodes in the direction of the flow of a gas mixture passed through an active zone between the electrodes where the laser effect is produced. The invention provides for a maximum efficiency of the laser under different operating conditions.
Kosyrev, F. K.; Leonov, A. P.; Pekh, A. K.; Timofeev, V. A.
Paint contaminated with radionuclides and other hazardous materials is common in Department of Energy (DOE) facilities. Facility decommissioning and decontamination requires the removal of contaminated paint. Paint removal technologies include laser- and abrasive-based systems. F2 Associates are utilizing a pulsed-repetition CO{sub 2} laser that produces a 2.5-cm x 2.5-cm beam which can be scanned across a 30- x 100-cm raster and, when placed on a robot, can be designed to clean any surface that the robot can be programmed to follow. Causing little or no damage to the substrate (concrete, steel, etc.), the laser ablates the material to be removed from a given surface. Ablated material is then pulled into a filtration and collection (VAC-PAC) system to prevent the hazardous substances from entering into the atmosphere. The VAC-PAC system deposits the ablated material into waste drums which may be removed from the system without compromising the integrity of the seal, allowing a new drum to be set up for collection without leakage of the ablated material into the atmosphere.
Grisanti, A.A.; Hassett, D.J.
Method for materials deposition by ablation transfer processing
A method in which a thin layer of semiconducting, insulating, or metallic material is transferred by ablation from a source substrate, coated uniformly with a thin layer of said material, to a target substrate, where said material is desired, with a pulsed, high intensity, patternable beam of energy. The use of a patternable beam allows area-selective ablation from the source substrate resulting in additive deposition of the material onto the target substrate which may require a very low percentage of the area to be covered. Since material is placed only where it is required, material waste can be minimized by reusing the source substrate for depositions on multiple target substrates. Due to the use of a pulsed, high intensity energy source the target substrate remains at low temperature during the process, and thus low-temperature, low cost transparent glass or plastic can be used as the target substrate. The method can be carried out atmospheric pressures and at room temperatures, thus eliminating vacuum systems normally required in materials deposition processes. This invention has particular application in the flat panel display industry, as well as minimizing materials waste and associated costs. 1 fig.
Weiner, K.H.
Method for materials deposition by ablation transfer processing
A method in which a thin layer of semiconducting, insulating, or metallic material is transferred by ablation from a source substrate, coated uniformly with a thin layer of said material, to a target substrate, where said material is desired, with a pulsed, high intensity, patternable beam of energy. The use of a patternable beam allows area-selective ablation from the source substrate resulting in additive deposition of the material onto the target substrate which may require a very low percentage of the area to be covered. Since material is placed only where it is required, material waste can be minimized by reusing the source substrate for depositions on multiple target substrates. Due to the use of a pulsed, high intensity energy source the target substrate remains at low temperature during the process, and thus low-temperature, low cost transparent glass or plastic can be used as the target substrate. The method can be carried out atmospheric pressures and at room temperatures, thus eliminating vacuum systems normally required in materials deposition processes. This invention has particular application in the flat panel display industry, as well as minimizing materials waste and associated costs.
Weiner, Kurt H. (San Jose, CA)
conduction, (2) electron-ion (exothermic) recombination on the cavity walls, (3) short-wavelength thermal plasmaconduction, electron-ion recombination and condensation of vapor on the cavity walls, and the plasma
Zeng, Xianzhong
Stagnation of Ablated Metal Vapor in Laser Fusion Reactor with Liquid Wall
height. The inner surface is covered with a 5-mm thick liquid Li17Pb83 flow as the first protective wall instead of Li17Pb83. A 300 m diameter, 4 m thick lead target was prepared on a glass plate by physical is the chamber wall and x=3 m is the center of the chamber. It is clearly shown that large clusters are formed
Ito, Atsushi
Polymer Stable Magnesium Nanocomposites Prepared by Laser Ablation for Efficient Hydrogen Storage
Hydrogen is a promising alternative energy carrier that can potentially facilitate the transition from fossil fuels to sources of clean energy because of its prominent advantages such as high energy density (142 MJ per kg), great variety of potential sources (for example water, biomass, organic matter), and low environmental impact (water is the sole combustion product). However, due to its light weight, the efficient storage of hydrogen is still an issue investigated intensely. Various solid media have been considered in that respect among which magnesium hydride stands out as a candidate offering distinct advantages. Recent theoretical work indicates that MgH2 becomes less thermodynamically stable as particle diameter decreases below 2 nm. Our DFT (density functional theory) modeling studies have shown that the smallest enthalpy change, corresponding to 2 unit-cell thickness (1.6 {\\AA} Mg/3.0{\\AA} MgH2) of the film, is 57.7 kJ/molMg. This enthalpy change is over 10 kJ per molMg smaller than that of the bulk...
Makridis, S S; Panagakos, G; Kikkinides, E S; Stubos, A K; Wagener, P; Barcikowski, S
Laser Ablation in Liquids: A Unique Route to Fabricate Hollow Micro ...
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, 2014 TMS Annual Meeting & Exhibition. Symposium , 2014 TMS RF Mehl Medal Symposium on Frontiers in Nanostructured�...
This paper describes an invention of a pressure measuring instrument which uses laser radiation to sense the pressure in an enclosed environment by means of measuring the change in refractive index of a gas - which is pressure dependent.
Abercrombie, K.R.; Shiels, D.; Rash, T.
Science Conference Proceedings (OSTI)
This report contains results of a coordinated, multi-laboratory investigation of coal devolatilization. Data is reported pertaining to the devolatilization for bituminous coals over three orders of magnitude in apparent heating rate (100 to 100,000 + {degree}C/sec), over two orders of magnitude in particle size (20 to 700 microns), final particle temperatures from 400 to 1600{degree}C, heat transfer modes ranging from convection to radiative, ambient pressure ranging from near vacuum to one atmosphere pressure. The heat transfer characteristics of the reactors are reported in detail. It is assumed the experimental results are to form the basis of a devolatilization data base. Empirical rate expressions are developed for each phase of devolatilization which, when coupled to an awareness of the heat transfer rate potential of a particular devolatilization reactor, indicate the kinetics emphasized by a particular system reactor plus coal sample. The analysis indicates the particular phase of devolatilization that will be emphasized by a particular reactor type and, thereby, the kinetic expressions appropriate to that devolatilization system. Engineering rate expressions are developed from the empirical rate expressions in the context of a fundamental understanding of coal devolatilization developed in the course of the investigation. 164 refs., 223 figs., 44 tabs.
Seery, D.J.; Freihaut, J.D.; Proscia, W.M. (United Technologies Research Center, East Hartford, CT (USA)); Howard, J.B.; Peters, W.; Hsu, J.; Hajaligol, M.; Sarofim, A. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Jenkins, R.; Mallin, J.; Espindola-Merin, B. (Pennsylvania State Univ., University Park, PA (USA)); Essenhigh, R.; Misra, M.K. (Ohio State Univ., Columbus, OH (USA))
Amber Kinetics | Open Energy Information
search Name Amber Kinetics Product Start-up company developing a novel flywheel energy storage system with the Lawrence Livermore National Laboratory. References Amber...
Science Conference Proceedings (OSTI)
It is shown that the model of the defect-deformation instability describes the recently found linear dependence of the period of ordered surface relief microstructures, produced on brass in liquid upon multipulse laser ablation, on the radius of the spot on the target surface. (letters)
Emel'yanov, V I [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)
Detection and Investigation of Carbon Ions Induced by Nd:YAG laser using SSNTDs
Science Conference Proceedings (OSTI)
A Q-Switched Nd:YAG laser pulse of pulsed width of 9{approx}14 ns, wavelength of 1064 nm, repetition rate of 0.5 Hz, power of 1.1 MW and energy of 10 mJ has been used to ablate the 4N pure graphite target through IR lens. Solid state nuclear track detector (SSNTD) CR-39 has been used to calculate the energy of carbon ions produced as a result of laser ablation and the whole experiment has been performed under pressure {approx}10{sup -3} Torr in stainless steel vacuum chamber. The minimum and maximum energy of carbon ions observed are 0.2 KeV to 250 KeV respectively.
Qindeel, Rabia; Ali, Jalil Bin; Chaudhary, K. T. [Advance Photonic Science Institute, EsciNano Research Alliance, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai, 81310, Johor Bahru (Malaysia); Hussain, M. S. [Department of Materials Engineering, Faculty of Mechanical Engineering UTM, 81300 Johor Bahru (Malaysia)
Technical Note: Simulating chemical systems in Fortran90 and Matlab with the Kinetic PreProcessor KPP-2.1 A estimation techniques, and variational chemical data assimilation applications require the development of ef- ficient tools for the computational simulation of chemical kinetics systems. From a numerical point
Paris-Sud XI, Université de
Nonlinear effects in kinetic resolutions
The impact of nonlinear effects in the asymmetric catalysis of kinetic resolutions is analyzed. It is found with minimal assumptions that the kinetics of homocompetitive reactions should apply generally to kinetic resolutions involving partially resolved catalysts, and this is supported by experimental observations with the Jacobsen hydrolytic kinetic resolution (HKR) of epoxides. The criterion for a nonlinear effect in asymmetric catalysis--a nonlinear correlation between the enantiomeric excess in a choral ligand and the product enantiomeric excess obtained from a reaction--is examined. The nonlinear effect idea is found to be generalizable to kinetic resolutions and other reactions by replacing consideration of the product enantiomeric excess with the quantity (k[]/k[]-1)/(k[]/k[]+1), a differential kinetic enantiomeric enhancement (DKEE). A nonlinear effect may then be defined by a nonlinear correlation between the DKEE and the chiral ligand enantiomeric excess. The application of these ideas to previously reported kinetic resolutions of sulfoxides and to nonlinear effects in the Jacobsen HKR is described. Relatively small nonlinear effects in kinetic resolutions are sufficient to obtain large asymmetric amplifications. A catalyst modification in the Jacobsen HKR also allows for the development of a novel recyclable system for the iterative enhancement of optical activity.
Johnson, Derrell W.
Science Conference Proceedings (OSTI)
Dimensional Measurements. Laser Measurements. Rate our Services. Technical ... Laser Frequency/Wavelength (14510S-14511S). The ...
Laser Beam Delivery [Laser Applications Laboratory] - Nuclear...
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Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities...
Lasers and Optoelectronic Components Used with Lasers
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... example, beam profile and relative intensity noise ... for the laser wavelengths and energies for which ... The laser power and energy measurements are ...
A pressure measuring instrument that utilizes the change of the refractive index of a gas as a function of pressure and the coherent nature of a laser light to determine the barometric pressure within an environment. As the gas pressure in a closed environment varies, the index of refraction of the gas changes. The amount of change is a function of the gas pressure. By illuminating the gas with a laser light source, causing the wavelength of the light to change, pressure can be quantified by measuring the shift in fringes (alternating light and dark bands produced when coherent light is mixed) in an interferometer.
Abercrombie, Kevin R. (Westminster, CO); Shiels, David (Thornton, CO); Rash, Tim (Aurora, CO)
Thermodynamics and Kinetics Information at NIST
Science Conference Proceedings (OSTI)
... Staff (06/28/2013). Thermodynamic & Kinetic Data for Sustainable Energy (10/05/2012). Thermodynamics and Kinetics Group (07/06/2013 ...
Flight Experiments On Energy Scaling For In-Space Laser Propulsion
As a preparatory study on space-borne laser propulsion, flight experiments with a parabolic thruster were carried out on an air cushion table. The thruster was mounted like a sail on a puck, allowing for laser-driven motion in three degrees of freedom (3 DOF) in artificial weightlessness. Momentum coupling is derived from point explosion theory for various parabolic thruster geometries with respect to energy scaling issues. The experimental data are compared with theoretical predictions and with results from vertical free flights. Experimental results for the air-breakdown threshold and POM ablation inside the thruster are compared with fluence data from beam propagation modeling.
Scharring, Stefan; Eckel, Hans-Albert [Institute of Technical Physics, German Aerospace Center, D-70569 Stuttgart, Pfaffenwaldring 38-40 (Germany); Wollenhaupt, Eric; Roeser, Hans-Peter [Institute of Space Systems, University of Stuttgart, D-70569 Stuttgart, Pfaffenwaldring 31 (Germany)
Laser wavelength effects in ultrafast near-field laser nanostructuring...
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Laser wavelength effects in ultrafast near-field laser nanostructuring of Si Title Laser wavelength effects in ultrafast near-field laser nanostructuring of Si Publication Type...
EA-1655: Berkeley Lab Laser Accelerator (BELLA) Laser Acquisition...
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
655: Berkeley Lab Laser Accelerator (BELLA) Laser Acquisition, Installation and Use for Research and Development EA-1655: Berkeley Lab Laser Accelerator (BELLA) Laser Acquisition,...
Observation and Parameterization of Ablation at the Base of Ronne Ice Shelf, Antarctica
Science Conference Proceedings (OSTI)
Parameterizations of turbulent transfer through the oceanic boundary layer beneath an ice shelf are tested using direct measurements of basal ablation. Observations were made in the southwestern part of Ronne Ice Shelf, about 500 km from open ...
Adrian Jenkins; Keith W. Nicholls; Hugh F. J. Corr
Improved Spatial Filter for high power Lasers
A new pinhole architecture incorporates features intended to reduce the rate of plasma generation in a spatial filter for high-energy laser pulse beams. An elongated pinhole aperture is provided in an apertured body for rejecting off-axis rays of the laser pulse beam. The internal surface of the elongated aperture has a diameter which progressively tapers from a larger entrance cross-sectional area at an inlet to a smaller output cross-sectional area at an outlet. The tapered internal surface causes off-axis rays to be refracted in a low density plasma layer that forms on the internal surface or specularly reflected at grazing incidence from the internal surface. Off-axis rays of the high-energy pulse beam are rejected by this design. The external surface of the apertured body adjacent to the larger entrance cross-sectional area at the inlet to the elongated aperture is angled obliquely with respect to the to direction of the path of the high-energy laser pulse beam to backscatter off-axis rays away from the high-energy pulse beam. The aperture is formed as a truncated cone or alternatively with a tapered square cross-section. The internal surface of the aperture is coated with an ablative material, preferably high-density material which can be deposited with an exploding wire.
Estabrook, Kent G.; Celliers, Peter M.; Murray, James E.; DaSilva, Luiz; MacGowan, Brian J.; Rubenchik, Alexander M.; Manes, Kenneth R.; Drake, Robert P.; Afeyan, Bedros
This paper describes the coupling of ambient laser ablation surface sampling, accomplished using a laser capture microdissection system, with atmospheric pressure chemical ionization mass spectrometry for high spatial resolution multimodal imaging. A commercial laser capture microdissection system was placed in close proximity to a modified ion source of a mass spectrometer designed to allow for sampling of laser ablated material via a transfer tube directly into the ionization region. Rhodamine 6G dye of red sharpie ink in a laser etched pattern as well as cholesterol and phosphatidylcholine in a cerebellum mouse brain thin tissue section were identified and imaged from full scan mass spectra. A minimal spot diameter of 8 m was achieved using the 10X microscope cutting objective with a lateral oversampling pixel resolution of about 3.7 m. Distinguishing between features approximately 13 m apart in a cerebellum mouse brain thin tissue section was demonstrated in a multimodal fashion including co-registered optical and mass spectral chemical images.
Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL
Metal reduction kinetics in Shewanella
Science Conference Proceedings (OSTI)
Motivation: Metal reduction kinetics have been studied in cultures of dissimilatory metal reducing bacteria which include the Shewanella oneidensis strain MR-1. Estimation of system parameters from time-series data faces obstructions in ...
Raman Lall; Julie Mitchell
Beamed Energy Propulsion by Means of Target Ablation
Science Conference Proceedings (OSTI)
This paper describes hundreds of pendulum tests examining the beamed energy conversion efficiency of different metal targets coated with multiple liquid enhancers. Preliminary testing used a local laser with photographic paper targets, with no liquid, water, canola oil, or methanol additives. Laboratory experimentation was completed at Wright-Patterson AFB using a high-powered laser, and ballistic pendulums of aluminum, titanium, or copper. Dry targets, and those coated with water, methanol and oil were repeatedly tested in laboratory conditions. Results were recorded on several high-speed digital video cameras, and the conversion efficiency was calculated. Paper airplanes successfully launched using BEP were likewise recorded.
Rosenberg, Benjamin A. [Hilton Head High School, Hilton Head Island, SC 29926 (United States)
Theoretical Studies in Chemical Kinetics
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Theoretical Studies in Chemical Kinetics ^ ^ iCi| Theoretical Studies in Chemical Kinetics ^ ^ iCi| under AEC Contract A T (30-1)-3780 " ■ ' Annual Report (1970) Principal In-vestigator: Martin Karpins Institution: Harvard University The research performed under this contract can best be sunmarized under several headings. (a) Alkali-Halideg Alkali-Halide (MX^ M*X*) Exchange Reactions. This project is being continued. A careful study of certain
Advances in petascale kinetic plasma simulation with VPIC and Roadrunner
VPIC, a first-principles 3d electromagnetic charge-conserving relativistic kinetic particle-in-cell (PIC) code, was recently adapted to run on Los Alamos's Roadrunner, the first supercomputer to break a petaflop (10{sup 15} floating point operations per second) in the TOP500 supercomputer performance rankings. They give a brief overview of the modeling capabilities and optimization techniques used in VPIC and the computational characteristics of petascale supercomputers like Roadrunner. They then discuss three applications enabled by VPIC's unprecedented performance on Roadrunner: modeling laser plasma interaction in upcoming inertial confinement fusion experiments at the National Ignition Facility (NIF), modeling short pulse laser GeV ion acceleration and modeling reconnection in magnetic confinement fusion experiments.
Bowers, Kevin J [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Yin, Lin [Los Alamos National Laboratory; Daughton, William S [Los Alamos National Laboratory; Roytershteyn, Vadim [Los Alamos National Laboratory; Kwan, Thomas J T [Los Alamos National Laboratory
Driving high-gain shock-ignited inertial confinement fusion targets by green laser light
Science Conference Proceedings (OSTI)
Standard direct-drive inertial confinement fusion requires UV light irradiation in order to achieve ignition at total laser energy of the order of 1 MJ. The shock-ignition approach opens up the possibility of igniting fusion targets using green light by reducing the implosion velocity and laser-driven ablation pressure. An analytical model is derived, allowing to rescale UV-driven targets to green light. Gain in the range 100-200 is obtained for total laser energy in the range 1.5-3 MJ. With respect to the original UV design, the rescaled targets are less sensitive to irradiation asymmetries and hydrodynamic instabilities, while operating in the same laser-plasma interaction regime.
Atzeni, Stefano; Marocchino, Alberto; Schiavi, Angelo [Dipartimento SBAI, Universita di Roma 'La Sapienza' and CNISM, Via A. Scarpa 14-16, I-00161 Roma (Italy)
Modification of earth-satellite orbits using medium-energy pulsed lasers
Laser Impulse Space Propulsion (LISP) has become an attractive concept, due to recent advances in gas laser technology, high-speed segmented mirrors and improved coeffici-ents for momentum coupling to targets in pulsed laser ablation. There are numerous specialized applications of the basic concept to space science-ranging from far-future and high capital cost to the immediate and inexpensive, such as: LEO-LISP (launch of massive objects into low-Earth-Orbit at dramatically improved cost-per-kg relative to present practice); LEGO-LISP (LEO to geosynchronous transfers); LO-LISP) (periodic re-boost of decaying LEO orbits); and LISK (geosynchronous satellite station-keeping). It is unlikely that one type of laser will be best for all scenarios. In this paper, we will focus on the last two applications.
Phipps, C.R.
Modification of earth-satellite orbits using medium-energy pulsed lasers
Laser Impulse Space Propulsion (LISP) has become an attractive concept, due to recent advances in gas laser technology, high-speed segmented mirrors and improved coeffici-ents for momentum coupling to targets in pulsed laser ablation. There are numerous specialized applications of the basic concept to space science-ranging from far-future and high capital cost to the immediate and inexpensive, such as: LEO-LISP (launch of massive objects into low-Earth-Orbit at dramatically improved cost-per-kg relative to present practice); LEGO-LISP (LEO to geosynchronous transfers); LO-LISP) (periodic re-boost of decaying LEO orbits); and LISK (geosynchronous satellite station-keeping). It is unlikely that one type of laser will be best for all scenarios. In this paper, we will focus on the last two applications.
Phipps, C.R.
Heterodyne laser diagnostic system
The heterodyne laser diagnostic system includes, in one embodiment, an average power pulsed laser optical spectrum analyzer for determining the average power of the pulsed laser. In another embodiment, the system includes a pulsed laser instantaneous optical frequency measurement for determining the instantaneous optical frequency of the pulsed laser.
Globig, Michael A. (Antioch, CA); Johnson, Michael A. (Pleasanton, CA); Wyeth, Richard W. (Livermore, CA)
Defect aggregation kinetics in calcium fluoride
Science Conference Proceedings (OSTI)
Defects in solid materials are responsible for many of their most interesting and critical properties. The authors have developed a site-selective laser technique that allows us to monitor the aggregation of rare earth ion defects in solids on the microscopic scale. This excitation absorption laser method enables us to derive kinetic rate information and thermodynamic parameters for the distribution of defects in solids. For doped materials, various types of defects arise when the dopant ions have ionic charges that differ from the charges of host crystal ions. In model systems such as alkaline earth fluorides doped with trivalent rare earth ions, some defect sites consist of a single dopant ion, while others consist of clusters of dopant cations and interstitial anions. Heat treatment of doped samples leads to a distribution of the various types of defect sites that is characteristic of the temperature and length of heat treatment and the total dopant ion concentration. The results from a study of the formation of trivalent europium ion defect aggregates in calcium fluoride indicate that our method successfully monitors changes in individual site concentrations resulting from heat treatment. The results of this study are consistent with the formation of negatively charged dimer and trimer defects in Eu{sup 3+}:CaF{sub 2} crystals from isolated europium ion and (Eu:F{sub i}) single pair defects. In addition, he presents evidence for rapid equilibrium between the isolated ion and the single pair. Other work presented in this thesis includes the development of a high-temperature fluorine oxidation apparatus that was used to convert divalent europium ions to the trivalent state in calcium fluoride single crystals. This apparatus was also used to increase the superconducting {Tc}'s of YBa{sub 2}Cu{sub 3}O{sub 7-x} through modification of copper-oxygen oxidation states.
Cirillo, K.M.
Deposition of DLC via intense ion beam ablation
Science Conference Proceedings (OSTI)
Diamond-like carbon films were prepared by high intensity pulsed ion beam ablation of graphite targets. A 350 key, 35 kA, 400 ns pulse width beam, consisting primarily of carbon ions and protons, was focused onto a graphite target at a fluence of 15-45J/cm{sup 2}. Films were deposited onto substrates positioned i.n q n angular array from normal to the target to 90{degrees} off normal. Deposition rates up to 30 nm per pulse, corresponding to an instantaneous deposition rate greater than I mn/sec, have been observed. Electrical resistivities between 1 and 1000 ohm-cm were measured for these films. XRD scans showed that no crystalline structure developed in the films. SEM revealed that the bulk of the films contain material with feature sizes on the order of 100 nm, but micron size particles were deposited as well. Both Raman and electron energy loss spectroscopy indicated significant amounts of sp{sup 3} bonded carbon present in most of the films.
Johnston, G.P. [Los Alamos National Lab., NM (United States)]|[Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical Engineering; Tiwari, P.; Rej, D.J.; Davis, H.A.; Waganaar, W.J.; Muenchausen, R.E. [Los Alamos National Lab., NM (United States); Tallant, D.; Simpson, R.L. [Sandia National Lab., Albuquerque, NM (United States); Williams, D.B. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Metallurgy and Materials Engineering; Qui, X. [Univ. of New Mexico, Albuquerque, NM (United States). Dept of Chemical Engineering
Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials
Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.
Mcgrane, Shawn David [Los Alamos National Laboratory; Bolme, Cindy B [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory
Environment/Health/Safety (EHS): Laser Safety
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Laser Safety Home Whom to Call Analysis of Laser Safety Occurrences: 2005-2011 Laser Bio-effects Laser Classification Laser Disposal Guide Laser Forms Laser Newsletter Laser Lab...
Modeling of high energy laser ignition of energetic materials
We present a model for simulating high energy laser heating and ignition of confined energetic materials. The model considers the effect of irradiating a steel plate with long laser pulses and continuous lasers of several kilowatts and the thermal response of well-characterized high explosives for ignition. Since there is enough time for the thermal wave to propagate into the target and to create a region of hot spot in the high explosives, electron thermal diffusion of ultrashort (femto- and picosecond) lasing is ignored; instead, heat diffusion of absorbed laser energy in the solid target is modeled with thermal decomposition kinetic models of high explosives. Numerically simulated pulsed-laser heating of solid target and thermal explosion of cyclotrimethylenetrinitramine, triaminotrinitrobenzene, and octahydrotetranitrotetrazine are compared to experimental results. The experimental and numerical results are in good agreement.
Lee, Kyung-cheol; Kim, Ki-hong; Yoh, Jack J. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-742 (Korea, Republic of)
Tailoring the air plasma with a double laser pulse
We present a comprehensive model of plasma dynamics that enables a detailed understanding of the ways the air plasma induced in the atmosphere in the wake of a laser-induced filament can be controlled by an additional laser pulse. Our model self-consistently integrates plasma-kinetic, Navier-Stokes, electron heat conduction, and electron-vibration energy transfer equations, serving to reveal laser-plasma interaction regimes where the plasma lifetime can be substantially increased through an efficient control over plasma temperature, as well as suppression of attachment and recombination processes. The model is used to quantify the limitations on the length of uniform laser-filament heating due to the self-defocusing of laser radiation by the radial profile of electron density. The envisaged applications include sustaining plasma guides for long-distance transmission of microwaves, standoff detection of impurities and potentially hazardous agents, as well as lightning control and protection.
Shneider, M. N.; Miles, R. B. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States); Zheltikov, A. M. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843-4242 (United States)
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all the way through college physics. Let me try anyway, but first let's define what a laser and laser light are. Laser is an acronym for Light Amplification by Stimulated...
The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.
Perry, Michael D. (Livermore, CA); Stuart, Brent C. (Fremont, CA); Banks, Paul S. (Livermore, CA); Myers, Booth R. (Livermore, CA); Sefcik, Joseph A. (Tracy, CA)
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Free Electron Laser Building Exterior Top Floor Control Room RF Gallery User Lab Beam Enclosure Injector Linear Accelerator Wiggler Magnet Return Line Free Electron Laser Most...
A review of experimental and theoretical concepts of a free electron laser is given. The possibilities of scaling these lasers to high powers are discussed. (MOW)
Brau, C.A.
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Previous Video (Hybrid Meson) Physics Out Loud Main Index Next Video (Matter) Matter Laser Learn all about different types of lasers with Jefferson Lab's Michelle Shinn, a...
?? A Laser Music System has been created, that combines a laser and light sensor system with an infrared distance sensing system that detects the� (more)
Woodruff, Astra
Femtosecond Laser Frequency Combs
Science Conference Proceedings (OSTI)
... to all of these is the continued development of the lasers themselves. We are exploring and comparing different types of fs-laser comb technology ...
Temperature controlled multiple pass absorption cell for gas phase chemical kinetics studies
Science Conference Proceedings (OSTI)
The application of a Herriott-type optical multiple pass cell for absorption detection of transient species in temperature controlled laser pump-probe kinetics experiments is described. Using reaction initiation by laser photolysis in combination with reaction monitoring by absorption of a multiple pass laser allows confinement of the probed reaction volume to the temperature controlled region of a slow flow reactor. For transient measurements, this apparatus provides enhanced sensitivity from increased path length and accurate temperature control by limiting the pump-probe interaction volume. In addition, for a polarized probe laser, a simple arrangement using a polarizing beam splitter and a {lambda}/4 plate allows doubling of the path length. {copyright} {ital 1997 American Institute of Physics.}
Pilgrim, J.S.; Jennings, R.T.; Taatjes, C.A. [Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969 (United States)
Experimental investigation of the dynamics of pellet ablation on the Texas Experimental Tokamak
Science Conference Proceedings (OSTI)
Rapid fluctuations in the ablation of hydrogen pellets in the Texas Experimental Tokamak were studied using fast photographic techniques. It is proposed that the fluctuations are a type of relaxation oscillation driven by the motion of the particle across the magnetic field. This is shown to be consistent with a time-dependent model of plasma shielding due to Kaufmann et al. A technique to include this effect in calculations of pellet ablation is discussed. Spatially resolved measurements of the temperature and density in the pellet-ablation cloud were obtained by line-to-continuum ratios and Stark broadening, respectively. Typical parameters in the pellet-ablation cloud are 5-6 eV and 1.0-1.5 {times} 10{sup 17} cm{sup {minus}3}. The flow along the magnetic field is found to be isobaric. The heating of the expanding ablatant is strongly asymmetric, being stronger on the side facing the electron-drift direction. This may be due to suprathermal electrons.
Durst, R.D.
Experimental Studies of ICF Indirect-Drive Be and High Density C Candidate Ablators
Science Conference Proceedings (OSTI)
To validate our modeling of the macroscopic and microscopic hydrodynamic and equation of state response of these candidate ablators to NIC-relevant x-ray drive, a multi-lab experimental program has been verifying the behavior of these new ablators. First, the pressures for onset and termination of melt for both Be and HDC under single or double shock drive has been measured at the Z and Omega facilities. Second, the level and effect of hard x-ray preheat has been quantified in scaled experiments at the Omega facility. Third, a long planar x-ray drive has been developed to check 2D and 3D perturbation growth at the ablation front upon acceleration. The concept has been extended to study growth at and near the ablator-ice interface upon deceleration. In addition, experimental designs for validating the expected low level of perturbation seeding due to possible residual microstructure after melt during first and second shock transit in Be and HDC have been completed. Results so far suggest both Be and HDC can remain ablator choices and have guided pulse shaping designs.
Landen, O L; Bradley, D K; Braun, D G; A.Smalyuk, V; Hicks, D G; Celliers, P M; Prisbrey, S; Page, R; Boehly, T R; Haan, S W; Munro, D H; Wallace, R G; Nikroo, A; Hamza, A; Biener, J; Wild, C; Woerner, E; Olson, R E; Rochau, G A; Knudson, M; Wilson, D C; Robey, H F; Collins, G W; Ho, D; Edwards, J; Marinak, M M; Hammel, B A; Meyerhofer, D D; MacGowan, B J
Micro-Crater Laser Induced Breakdown Spectroscopy--an Analytical approach in metals samples
Science Conference Proceedings (OSTI)
The laser ablation has been increasing its popularity like as technique of chemical analysis. This is due to its great potentiality in the analysis of solid samples. On the way to contributing to the development of the technique, we in this work studied the laser induced breakdown spectroscopy (LIBS) in conditions of micro ablation for future studies of coverings and micro crates analysis. Craters between 2 and 7 micrometers of diameter were made using an Nd-YAG nanosecond laser in their fundamental emission of 1064 nm. In order to create these craters we use an objective lens of long distance work and 0.45 of numerical aperture. The atomic emission versus the energy of the laser and its effect on the size of craters was study. We found that below 3 micrometers although there was evidence of material removal by the formation of a crater, it was no detectable atomic emission for our instruments. In order to try to understand this, curves of size of crater versus plasma temperature using the Boltzmann distribution graphs taking the Copper emission lines in the visible region were made. In addition calibration curves for Copper and aluminum were made in two different matrices; one of it was a Cu/Zn alloy and the other a Zinc Matrix. The atomic lines Cu I (521.78 nm) and Al I (396.15 nm) was used. From the Calibration curve the analytical limit of detection and other analytical parameters were obtained.
Piscitelli, Vincent [UCV- Laboratorio de Espectroscopia Laser, Caracas (Venezuela); Lawrence Berkeley National laboratory, Berkeley, US (United States); Gonzalez, Jhanis; Mao Xianglei; Russo, Richard [Lawrence Berkeley National laboratory, Berkeley, US (United States); Fernandez, Alberto [UCV- Laboratorio de Espectroscopia Laser, Caracas (Venezuela)
Laser program at LASL. Progress report, January 1--June 30, 1975
Progress in the development of high-power lasers for fusion application is reported. Modifications to the Nd:glass system are described, and studies relating to specific problems of this system are summarized. Efforts in the development of a powerful CO$sub 2$ laser system are outlined, leading from a 1- kJ laser to a 2.5-kJ system and subsequently to a 10-kJ assembly. Results of experiments with the cold-cathode electron gun to be used in the 2.5-kJ system are given. Preliminary design criteria for a high-energy laser facility to accommodate an advanced CO$sub 2$ laser system with a nominal energy output of 100 kJ are discussed. Results of experimental studies on the high-gain HF system are presented; and several promising prospective molecular lasing systems are described. New methods of fabricating complex laser targets are summarized, and novel coating and inspection techniques are outlined. The development and testing of new instrumentation and data-acquisition techniques applicable to large laser systems and to experiments of greater complexity are described. Computer-code modifications and developments are discussed which integrate some of the phenomena observed in laser/target interaction experiments. Optimum radii, aspect ratios, and masses of targets for given laser time scales and energies are given, and the role of radiative preheating from a high-Z ablator in explaining the low performance in present laser-fusion experiments is outlined. Major efforts in recent feasibility and systems studies of laser-fusion power plants are described, and applications of laser fusion other than the direct production of electric power, e.g., the production of synthetic fuels, are discussed.
Skoberne, F.
of lesion formation at 3 Tesla Gaston R. Vergara, MD,* Sathya Vijayakumar, MS,* Eugene G. Kholmovski, Ph. In this study, we report a novel 3-Tesla RT -RI based porcine RF ablation model and visuali- zation of lesion-Tesla RT MRI-based catheter ablation and lesion visualization system. METHODS RF energy was delivered
Utah, University of
Preheating ablation effects on the Rayleigh-Taylor instability in the weakly nonlinear regime
The two-dimensional Rayleigh-Taylor instability (RTI) with and without thermal conduction is investigated by numerical simulation in the weakly nonlinear regime. A preheat model {kappa}(T)={kappa}{sub SH}[1+f(T)] is introduced for the thermal conduction [W. H. Ye, W. Y. Zhang, and X. T. He, Phys. Rev. E 65, 057401 (2002)], where {kappa}{sub SH} is the Spitzer-Haerm electron thermal conductivity coefficient and f(T) models the preheating tongue effect in the cold plasma ahead of the ablation front. The preheating ablation effects on the RTI are studied by comparing the RTI with and without thermal conduction with identical density profile relevant to inertial confinement fusion experiments. It is found that the ablation effects strongly influence the mode coupling process, especially with short perturbation wavelength. Overall, the ablation effects stabilize the RTI. First, the linear growth rate is reduced, especially for short perturbation wavelengths and a cutoff wavelength is observed in simulations. Second, the second harmonic generation is reduced for short perturbation wavelengths. Third, the third-order negative feedback to the fundamental mode is strengthened, which plays a stabilization role. Finally, on the contrary, the ablation effects increase the generation of the third harmonic when the perturbation wavelengths are long. Our simulation results indicate that, in the weakly nonlinear regime, the ablation effects are weakened as the perturbation wavelength is increased. Numerical results obtained are in general agreement with the recent weakly nonlinear theories as proposed in [J. Sanz, J. Ramirez, R. Ramis et al., Phys. Rev. Lett. 89, 195002 (2002); J. Garnier, P.-A. Raviart, C. Cherfils-Clerouin et al., Phys. Rev. Lett. 90, 185003 (2003)].
Wang, L. F. [SMCE, China University of Mining and Technology, Beijing 100083 (China); CAPT, Peking University, Beijing 100871 (China) and LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Department of Mathematics, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Ye, W. H.; He, X. T. [CAPT, Peking University, Beijing 100871 (China) and LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Department of Physics, Zhejiang University, Hangzhou 310027 (China); Sheng, Z. M. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Don, Wai-Sun [Department of Mathematics, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Li, Y. J. [SMCE, China University of Mining and Technology, Beijing 100083 (China)
Laser-induced synthesis and decay of Tritium under exposure of solid targets in heavy water
The processes of laser-assisted synthesis of Tritium nuclei and their laser-induced decay in cold plasma in the vicinity of solid targets (Au, Ti, Se, etc.) immersed into heavy water are experimentally realized at peak laser intensity of 10E10-10E13 Watts per square centimeter. Initial stages of Tritium synthesis and their laser-induced beta-decay are interpreted on the basis of non-elastic interaction of plasma electrons having kinetic energy of 5-10 eV with nuclei of Deuterium and Tritium, respectively.
E. V. Barmina; P. G. Kuzmin; S. F. Timashev; G. A. Shafeev
Longitudinal discharge laser baffles
The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam.
Warner, Bruce E. (Livermore, CA); Ault, Earl R. (Dublin, CA)
Longitudinal discharge laser baffles
The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam. 1 fig.
Warner, B.E.; Ault, E.R.
A short wavelength laser is provided that is driven by conventional-laser pulses. A multiplicity of panels, mounted on substrates, are supported in two separated and alternately staggered facing and parallel arrays disposed along an approximately linear path. When the panels are illuminated by the conventional-laser pulses, single pass EUV or soft x-ray laser pulses are produced.
Hagelstein, P.L.
A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables.
Milewski, John O. (Santa Fe, NM); Sklar, Edward (Santa Fe, NM)
A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables. 34 figs.
Milewski, J.O.; Sklar, E.
Kinetic Wave Power | Open Energy Information
Kinetic Wave Power Jump to: navigation, search Name Kinetic Wave Power Address 2861 N Tupelo St Place Midland Zip 48642 Sector Marine and Hydrokinetic Phone number 989-839-9757...
Laser Guiding for GeV Laser-Plasma Accelerators
Light pipe for high intensity laser pulses. Phys. Rev. Lett.and relativistically strong laser pulses in an underdensefrom Thomson scat- tering using laser wake?eld accelerators.
Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, C.B.; Toth, Csaba
Nonlinear laser energy depletion in laser-plasma accelerators
Nonlinear laser energydepletion in laser-plasma accelerators ? B. A. Shadwick,of intense, short-pulse lasers via excitation of plasma
Shadwick, B.A.
Laser Glazing of Railroad Rails [Laser Applications Laboratory] - Nuclear
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Laser Glazing of Railroad Laser Glazing of Railroad Rails Capabilities Engineering Experimentation Reactor Safety Experimentation Aerosol Experiments System Components Laser Applications Overview Laser Oil & Gas Well Drilling Laser Heat Treatment Laser Welding of Metals On-line Monitoring Laser Beam Delivery Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Laser Applications Laboratory Laser Glazing of Railroad Rails Project description: Laser glazing of rails. Category: Project with industrial partner (American Association of Railroads) Bookmark and Share
Laser Welding of Metals [Laser Applications Laboratory] - Nuclear
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Laser Welding of Metals Laser Welding of Metals Capabilities Engineering Experimentation Reactor Safety Experimentation Aerosol Experiments System Components Laser Applications Overview Laser Oil & Gas Well Drilling Laser Heat Treatment Laser Welding of Metals On-line Monitoring Laser Beam Delivery Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Laser Applications Laboratory Laser Welding of Metals Project description: High-speed laser welding of metals. Category: Project with industrial partner (Delphi Energy and Engine Management Systems) Bookmark and Share
Oxidation Kinetics Modeling Applying Phase Field Approach
Science Conference Proceedings (OSTI)
Presentation Title, Oxidation Kinetics Modeling Applying Phase Field Approach ... chemical reaction rates will increase exponentially and environmental attack�...
Modeling & Characterization of Harvestable Kinetic Energy for ...
Science Conference Proceedings (OSTI)
... gov 301.975-5479. Modeling & Characterization of Harvestable Kinetic Energy for Wearable Medical Sensors. RF-enabled ...
Kinetics of Nano Ti Carbides Precipitation
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, Materials Science & Technology 2011. Symposium, Steel Product Metallurgy and Applications. Presentation Title, Kinetics of Nano�...
The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation was studied by in situ optical observation. The average periods of the structures are much less than the sizes of the laser spots. The polarization reversal occurs through covering of the whole irradiated area by the nets of the spatially separated nanodomain chains and microdomain rays--''hatching effect.'' The main stages of the anisotropic nanodomain kinetics: nucleation, growth, and branching, have been singled out. The observed abnormal domain kinetics was attributed to the action of the pyroelectric field arising during cooling after laser heating.
Shur, V. Ya.; Kuznetsov, D. K.; Mingaliev, E. A.; Yakunina, E. M.; Lobov, A. I.; Ievlev, A. V. [Ferroelectric Laboratory, Institute of Physics and Applied Mathematics, Ural State University, Lenin Ave. 51, Ekaterinburg 620083 (Russian Federation)
Laser photolysis of fluorone dyes in a chitosan matrix
Kinetics of laser-induced photobleaching of fluorone dyes (fluorescein, dibromofluorescein, eosin Y, erythrosin B, Rose Bengal) is studied in a chitosan matrix. For all dyes the bleaching kinetics at the intensities of laser radiation 0.7 - 11.9 W cm{sup -2} demonstrates quasi-monomolecular behaviour. The results are analysed using a kinetic model, based on the four-level (S{sub 0}, S{sub 1}, T{sub 1}, T{sub n}) scheme of the dye with chemically active triplet states taken into account. It is shown that the rate constants of the chemical reaction involving higher triplet states in the dyes studied amount to (3.9 - 18.6) Multiplication-Sign 10{sup 6} s{sup -1} and exceed the analogous values for the reaction involving the first lower triplet states by nine orders of magnitude. The rate of reaction involving the first triplet states appeared to be higher by one - two orders of magnitude than that in the case of higher triplet states involved because of low population of the latter. The possible mechanism of dye bleaching with participation of chitosan that consists in reduction of the dye to the leuco form by transfer of hydrogen from the chitosan matrix is discussed. (interaction of laser radiation with matter. laser plasmas)
Slyusareva, E A; Sizykh, A G; Gerasimova, M A; Slabko, V V; Myslivets, S A
Non-stoichiometric material transfer in the pulsed laser deposition of LaAlO3
Inequivalent angular distributions have been found for La and Al in the ablation plume from LaAlO3 single crystal targets using a KrF laser during pulsed laser deposition. Angular distributions and stoichiometries in the condensate were measured and reveal decidedly non-stoichiometric transfer from target to substrate over most of the angular range. Composition varied dramatically for plume angles parallel to the long axis of the laser spot with the on-axis position exhibiting a peak in the La/Al atom ratio at ~1.5. The distributions were more diffuse in the perpendicular direction. Stoichiometric LaAlO3 was found in the condensate only at an extreme off-axis position.
Droubay, Timothy; Qiao, Liang; Kaspar, Tiffany C.; Engelhard, Mark H.; Shutthanandan, V.; Chambers, Scott A.
LANL | Physics | Trident Laser Facility
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science at Trident Laser Facility Several important discoveries and first observations have been made at the Trident Laser Facility, a unique three-beam neodymium-glass laser...
On fast reactor kinetics studies
Science Conference Proceedings (OSTI)
The results and the program of fast reactor core time and space kinetics experiments performed and planned to be performed at the IPPE critical facility is presented. The TIMER code was taken as computation support of the experimental work, which allows transient equations to be solved in 3-D geometry with multi-group diffusion approximation. The number of delayed neutron groups varies from 6 to 8. The code implements the solution of both transient neutron transfer problems: a direct one, where neutron flux density and its derivatives, such as reactor power, etc, are determined at each time step, and an inverse one for the point kinetics equation form, where such a parameter as reactivity is determined with a well-known reactor power time variation function. (authors)
Seleznev, E. F.; Belov, A. A. [Nuclear Safety Inst. of the Russian Academy of Sciences IBRAE (Russian Federation); Matveenko, I. P.; Zhukov, A. M.; Raskach, K. F. [Inst. for Physics and Power Engineering IPPE (Russian Federation)
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CO2 Laser CO2 Laser The ATF is one of the only two facilities worldwide operating picosecond, terawatt-class CO2 lasers. Our laser system consists of a picoseconds pulse-injector based on fast optical switching from the output of a conventional CO2 laser oscillator, and a chain of high-pressure laser amplifiers. It starts with a wavelength converter wherein a near-IR picosecond solid-state laser with l»1 μm produces a mid-IR 10-μm pulse. This process employs two methods; semiconductor optical switching, and the Kerr effect. First, we combine the outputs from a multi-nanosecond CO2 laser oscillator with a picosecond Nd:YAG laser on a germanium Brewster-plate to produce an ~200 ps, 10μm pulse by semiconductor optical switching. Co-propagating this pulse with a Nd:YAG's 2nd harmonic in a
An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.
Cantrell, Cyrus D. (Santa Fe, NM); Carbone, Robert J. (Los Alamos, NM); Cooper, Ralph S. (Los Alamos, NM)
An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.
Cantrell, Cyrus D. (Richardson, TX); Carbone, Robert J. (Johnson City, TN); Cooper, Ralph (Hayward, CA)
Purpose. Previous clinical studies have shown the safety and efficacy of this novel radiofrequency ablation catheter when used for endoscopic palliative procedures. We report a retrospective study with the results of first in man percutaneous intraductal radiofrequency ablation in patients with malignant biliary obstruction. Methods. Thirty-nine patients with inoperable malignant biliary obstruction were included. These patients underwent intraductal biliary radiofrequency ablation of their malignant biliary strictures following external biliary decompression with an internal-external biliary drainage. Following ablation, they had a metal stent inserted. Results. Following this intervention, there were no 30-day mortality, hemorrhage, bile duct perforation, bile leak, or pancreatitis. Of the 39 patients, 28 are alive and 10 patients are dead with a median survival of 89.5 (range 14-260) days and median stent patency of 84.5 (range 14-260) days. One patient was lost to follow-up. All but one patient had their stent patent at the time of last follow-up or death. One patient with stent blockage at 42 days postprocedure underwent percutaneous transhepatic drain insertion and restenting. Among the patients who are alive (n = 28) the median stent patency was 92 (range 14-260) days, whereas the patients who died (n = 10) had a median stent patency of 62.5 (range 38-210) days. Conclusions. In this group of patients, it appears that this new approach is feasible and safe. Efficacy remains to be proven in future, randomized, prospective studies.
Mizandari, Malkhaz [Tbilisi State Medical University, Department of Radiology (Georgia); Pai, Madhava, E-mail: firstname.lastname@example.com; Xi Feng [Imperial College, London, Hammersmith Hospital Campus, Department of Surgery (United Kingdom); Valek, Vlastimil; Tomas, Andrasina [University Hospital Brno Bohunice, Department of Radiology (Czech Republic); Quaretti, Pietro [IRCCS Policlinico San Matteo, Department of Radiology (Italy); Golfieri, Rita; Mosconi, Cristina [University of Bologna, Department of Radiology, Policlinico S. Orsola-Malpighi (Italy); Ao Guokun [The 309 Hospital of Chinese PLA, Department of Radiology (China); Kyriakides, Charis [Imperial College, London, Hammersmith Hospital Campus, Department of Surgery (United Kingdom); Dickinson, Robert [Imperial College London, Department of Bioengineering (United Kingdom); Nicholls, Joanna; Habib, Nagy, E-mail: email@example.com [Imperial College, London, Hammersmith Hospital Campus, Department of Surgery (United Kingdom)
A Model for Predicting Ice Accretion and Ablation in Water Bodies
Science Conference Proceedings (OSTI)
A model is presented for computing ice growth and ablation. Downward long- and shortwave radiation is computed for variable cloud amount and base. Surface albedo depends on snow cover and age of the snow or ice. Thermal inertia of the snow and ...
Maurice Danard; Mark Gray; Goz Lyv
Kinetically Dominated FRII Radio Sources
The existence of FR II objects that are kinetically dominated, the jet kinetic luminosity, $Q$, is larger than the total thermal luminosity (IR to X-ray) of the accretion flow, $L_{bol}$, is of profound theoretical interest. Such objects are not expected in most theoretical models of the central engine of radio loud AGN. Thus, establishing such a class of objects is an important diagnostic for filtering through the myriad of theoretical possibilities. This paper attempts to establish a class of quasars that have existed in a state of kinetic dominance, $R(t)\\equiv Q(t)/L_{bol}(t)>1$, at some epoch, $t$. It is argued that the 10 quasars in this article with a long term time average $Q(t)$, $\\bar{Q}$, that exceed $L_{Edd}$ are likely to have satisfied the condition $R(t)>1$ either presently or in the past based on the rarity of $L_{bol}>L_{Edd}$ quasars. Finally, the existence of these sources is discussed in the context of the theory of the central engine.
Brian Punsly
Laser Drilling with Gated High Power Fiber Lasers
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, Materials Science & Technology 2010. Symposium, Laser Applications in Materials Processing. Presentation Title, Laser Drilling�...
Laser Wakefield Acceleration Experiments Using HERCULES Laser
Science Conference Proceedings (OSTI)
Laser wakefield acceleration (LWFA) in a supersonic gas-jet using a self-guided laser pulse was studied by changing laser power and plasma electron density. The recently upgraded HERCULES laser facility equipped with wavefront correction enables a peak intensity of 6.1x10{sup 19} W/cm{sup 2} at laser power of 80 TW to be delivered to the gas-jet using F/10 focusing optics. We found that electron beam charge was increased significantly with an increase of laser power from 30 TW to 80 TW and showed density threshold behavior at a fixed laser power. We also studied the influence of laser focusing conditions by changing the f-number of the optics to F/15 and found an increase in density threshold for electron production compared to the F/10 configuration. The analysis of different phenomena such as betatron motion of electrons, side scattering of the laser pulse for different focusing conditions, the influence of plasma density down ramp on LWFA are shown.
Matsuoka, T.; McGuffey, C.; Dollar, F.; Bulanov, S. S.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K. [Center for Ultrafast Optical Science and FOCUS Center, University of Michigan, Ann Arbor, MI 48109 (United States); Horovitz, Y. [Center for Ultrafast Optical Science and FOCUS Center, University of Michigan, Ann Arbor, MI 48109 (United States); Dynamical Experiments Group, Propulsion Division, Soreq NRC, Yavnee 81800 (Israel)
NIST Laser Applications Staff Directory
Science Conference Proceedings (OSTI)
Laser Applications Staff Directory. Staff. Name, Position, Office Phone. ... Contact. Laser Applications Group Keith Lykke, Group Leader. ...
Possibility of nuclear pumped laser experiment using low enriched uranium
Possibility to perform experiments for nuclear pumped laser oscillation by using low enriched uranium is investigated. Kinetic analyses are performed for two types of reactor design, one is using highly enriched uranium and the other is using low enriched uranium. The reactor design is based on the experiment reactor in IPPE. The results show the oscillation of nuclear pumped laser in the case of low enriched uranium reactor is also possible. The use of low enriched uranium in the experiment will make experiment easier.
Obara, Toru; Takezawa, Hiroki [Center for Research into Innovative Nuclear Energy Systems Tokyo Institute of Technology 2-12-1-N1-19, Ookayama Meguro-ku, Tokyo 152-8550 (Japan)
Laser induced chemical reactions
of Basic Energy Sciences, Chemical Sciences Division of theINFRARED LASER ENHANCEMENT OF CHEMICAL REACTIONS A. B. C. D.Laser Inhibition of Chemical Reaction Effect of Isotopic
Orel, Ann E.
Atmospheric Laser Communication
Science Conference Proceedings (OSTI)
Atmospheric laser communication, often referred to as free-space optics (FSO) or free-space laser (FSL) communication, is similar to fiber optic cable in terms of carrier wavelength and bandwidth capability, but data are transmitted directly ...
Kenneth W. Fischer*Michael R. Witiw; Jeffrey A. Baars+; T. R. Oke
There is provided a direct nuclear pumped gas laser in which the lasing mechanism is collisional radiated recombination of ions. The gas laser active medium is a mixture of the gases, with one example being neon and nitrogen.
Miley, George H. (Champagne, IL); Wells, William E. (Urbana, IL); DeYoung, Russell J. (Hampton, VA)
1977. First Operation of a Free-Electron Laser. Phys . __Radiation from a High-Gain Free-Electeon Lasee Amplifier. ~1984. Variable-Wiggler Free-Electron-Laser Oscillat.ion.
Sessler, A.M.
Laser preheat enhanced ignition
A method for enhancing fuel ignition performance by preheating the fuel with laser light at a wavelength that is absorbable by the fuel prior to ignition with a second laser is provided.
Early, James W. (Los Alamos, NM)
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Argonne National Laboratory, July 17-19, 2007 Registration Form Workshop Agenda DOE Laser Safety Memo and Final Report, February 28, 2005 APS Laser OJT ANL CHM OJT Example...
Science Conference Proceedings (OSTI)
General Measurements for Laser Meters. ... 90 to 0 dBm. 0 to 30 dBm. AO 2005, Igor Vayshenker. Laser Dose, 193 nm, SP250-56, David Livigni. ...
Method and apparatus are provided for sorting particles, such as biological particles. A first laser is used to define an optical path having an intensity gradient which is effective to propel the particles along the path but which is sufficiently weak that the particles are not trapped in an axial direction. A probe laser beam is provided for interrogating the particles to identify predetermined phenotypical characteristics of the particles. A second laser beam is provided to intersect the driving first laser beam, wherein the second laser beam is activated by an output signal indicative of a predetermined characteristic. The second laser beam is switchable between a first intensity and a second intensity, where the first intensity is effective to displace selected particles from the driving laser beam and the second intensity is effective to propel selected particles along the deflection laser beam. The selected particles may then be propelled by the deflection beam to a location effective for further analysis. 2 figs.
Martin, J.C.; Buican, T.N.
Laser programs highlights 1993
Over the last two decades, the scope of our laser research has grown immensely. The small, low-power laser systems of our early days have given way to laser systems of record-breaking size and power. Now we are focusing our activities within the target physics and laser science programs to support the ignition and gain goals of the proposed glass-laser National Ignition Facility. In our laser isotope separation work, we completed the most important set of experiments in the history of the AVLIS Program in 1993, which culminated in a spectacularly successful run that met or exceeded all our objectives. We are also developing lasers and laser-related technologies for a variety of energy, commercial, and defense uses. On the horizon are transfers of important technologies for waste treatment, x-ray lithography, communications and security, optical imaging, and remote sensing, among others.
ESS 2012 Peer Review - Amber Kinetics Flywheel Energy Storage Demo - Ed Chiao, Amber Kinetics
Energy.gov (U.S. Department of Energy (DOE)) Indexed Site
amber_kinetics amber_kinetics DOE Peer Review September 2012 Ed Chiao, CEO amber_kinetics Amber Kinetics: Our Flywheel History Start-up launched in 2009, Stanford University Cleantech Entrepreneurship class Established a technology licensing & flywheel development partnership with LLNL; Amber Kinetics identified new material & lower-cost rotor designs for commercialization Awarded a Smart Grid Energy Storage Demonstration grant award for flywheels Awarded a matching grant for development & demonstration of flywheel technology Stanford University Lawrence Livermore National Laboratory U.S. Department of Energy California Energy Commission World-class institutions | innovative, deep flywheel technology owned by Amber Amber Kinetics, Inc. - Confidential and Proprietary, All Rights Reserved
Chemical Dynamics, Molecular Energetics, and Kinetics at the Synchrotron
Scientists at the Chemical Dynamics Beamline of the Advanced Light Source in Berkeley are continuously reinventing synchrotron investigations of physical chemistry and chemical physics with vacuum ultraviolet light. One of the unique aspects of a synchrotron for chemical physics research is the widely tunable vacuum ultraviolet light that permits threshold ionization of large molecules with minimal fragmentation. This provides novel opportunities to assess molecular energetics and reaction mechanisms, even beyond simple gas phase molecules. In this perspective, significant new directions utilizing the capabilities at the Chemical Dynamics Beamline are presented, along with an outlook for future synchrotron and free electron laser science in chemical dynamics. Among the established and emerging fields of investigations are cluster and biological molecule spectroscopy and structure, combustion flame chemistry mechanisms, radical kinetics and product isomer dynamics, aerosol heterogeneous chemistry, planetary and interstellar chemistry, and secondary neutral ion-beam desorption imaging of biological matter and materials chemistry.
Leone, Stephen R.; Ahmed, Musahid; Wilson, Kevin R.
Laser-induced damage in dielectrics with nanosecond to subpicosecond pulses. I. Experimental. Part 1
Science Conference Proceedings (OSTI)
The authors report extensive laser-induced damage threshold measurements on pure and multilayer dielectrics at 1053 and 526 mm for pulse durations, {tau}, ranging from 140 fs to 1 ns. Qualitative differences in the morphology of damage and a departure from the diffusion-dominated {tau}{sup 1/2} scaling indicate that damage results from plasma formation and ablation for {tau}{le}10 ps and from conventional melting and boiling for {tau}>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in good agreement with both the pulsewidth and wavelength scaling of experimental results.
Stuart, B.C.; Herman, S.; Perry, M.D.
Laser-Induced Damage of Calcium Fluoride
Science Conference Proceedings (OSTI)
As advances continue to be made in laser technology there is an increasing demand for materials that have high thresholds for laser-induced damage. Laser damage occurs when light is absorbed, creating defects in the crystal lattice. These defects can lead to the emission of atoms, ions and molecules from the sample. One specific field where laser damage is of serious concern is semiconductor lithography, which is beginning to use light at a wavelength of 157 nm. CaF2 is a candidate material for use in this new generation of lithography. In order to prevent unnecessary damage of optical components, it is necessary to understand the mechanisms for laser damage and the factors that serve to enhance it. In this research, we study various aspects of laser interactions with CaF2, including impurity absorbance and various forms of damage caused by incident laser light. Ultraviolet (UV) laser light at 266 nm with both femtosecond (fs) and nanosecond (ns) pulse widths is used to induce ion and neutral particle emission from cleaved samples of CaF2. The resulting mass spectra show significant differences suggesting that different mechanisms for desorption occur following excitation using the different pulse durations. Following irradiation by ns pulses at 266 nm, multiple single-photon absorption from defect states is likely responsible for ion emission whereas the fs case is driven by a multi-photon absorption process. This idea is further supported by the measurements made of the transmission and reflection of fs laser pulses at 266 nm, the results of which reveal a non-linear absorption process in effect at high incident intensities. In addition, the kinetic energy profiles of desorbed Ca and K contaminant atoms are different indicating that a different mechanism is responsible for their emission as well. Overall, these results show that purity plays a key role in the desorption of atoms from CaF2 when using ns pulses. On the other hand, once the irradiance reaches high levels, like that of the fs case, significant desorption is possible due to multi-photon absorption by the intrinsic material.
Espana, A.; Joly, A.G.; Hess, W.P.; Dickinson, J.T.
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, Materials Science & Technology 2010. Symposium, Laser Applications in Materials Processing. Presentation Title, The Effects of�...
Laser Technology and Applications
Science Conference Proceedings (OSTI)
... Major advances have been made in some areas: ? Specimen preparation using FIB ? Data collection rate ? Laser-assisted field evaporation ...
Science Conference Proceedings (OSTI)
Laser Measurements Seminar. June 16, 2005. *. Bookmark and Share. Contact: Michael Baum 301-975-2763. The 20th annual ...
Laser Heat Treatment [Laser Applications Laboratory] - Nuclear Engineering
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Heat Treatment Heat Treatment Capabilities Engineering Experimentation Reactor Safety Experimentation Aerosol Experiments System Components Laser Applications Overview Laser Oil & Gas Well Drilling Laser Heat Treatment Laser Welding of Metals On-line Monitoring Laser Beam Delivery Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Laser Applications Laboratory Laser Heat Treatment Project description: Optimization of laser beam heat treatment. Category: Project with industrial partner (Caterpillar and USCAR) Bookmark and Share Heat treatment optics
Kinetic Modeling of Microbiological Processes
Science Conference Proceedings (OSTI)
Kinetic description of microbiological processes is vital for the design and control of microbe-based biotechnologies such as waste water treatment, petroleum oil recovery, and contaminant attenuation and remediation. Various models have been proposed to describe microbiological processes. This editorial article discusses the advantages and limiation of these modeling approaches in cluding tranditional, Monod-type models and derivatives, and recently developed constraint-based approaches. The article also offers the future direction of modeling researches that best suit for petroleum and environmental biotechnologies.
Liu, Chongxuan; Fang, Yilin
Shale oil cracking. 1. Kinetics
Experiments were conducted to determine kinetics for thermal cracking of shale oil vapor over shale. Cracking temperatures of 504 to 610/sup 0/C and residence times of 2 to 11 seconds were used. A first-order Arrhenius rate expression and stoichiometry were obtained. Also observed were changes in the oil quality. Cracking decreased the H/C ratio, increased the nitrogen content, and decreased the pour point of the oil. Gas-phase oil cracking is contrasted to liquid-phase oil coking as a loss mechanism in oil-shale retorting.
Burnham, A.K.; Taylor, J.R.
Microreactor for fast chemical kinetics
The chemical reaction process in a T-shaped microchannel is studied experimentally through the reaction of Ca++ with a fluorescent tracer, Calcium-green. For thin channels (10 um), diffusion of species is found to behave in a way independent of the thickness direction. In such a situation, simulations of a two-dimensional reaction-diffusion model agree remarkably well with the experimental measurements. The comparison of experiments and simulations is used to measure the chemical kinetic constant, which we find to be k=3.2 x 10^5 dm^3/(mol s). Applications of the analysis to faster reactions and to micro-titration are also discussed.
Baroud, C N; Menetrier, L; Tabeling, P; Baroud, Charles N.; Okkels, Fridolin; Menetrier, Laure; Tabeling, Patrick
LaserFest was the yearlong celebration, during 2010, of the 50th anniversary of the demonstration of the first working laser. The goals of LaserFest were: to highlight the impact of the laser in its manifold commercial, industrial and medical applications, and as a tool for ongoing scientific research; to use the laser as one example that illustrates, more generally, the route from scientific innovation to technological application; to use the laser as a vehicle for outreach, to stimulate interest among students and the public in aspects of physical science; to recognize and honor the pioneers who developed the laser and its many applications; to increase awareness among policymakers of the importance of R&D funding as evidenced by such technology as lasers. One way in which LaserFest sought to meet its goals was to encourage relevant activities at a local level all across the country -- and also abroad -- that would be identified with the larger purposes of the celebration and would carry the LaserFest name. Organizers were encouraged to record and advertise these events through a continually updated web-based calendar. Four projects were explicitly detailed in the proposals: 1) LaserFest on the Road; 2) Videos; 3) Educational material; and 4) Laser Days.
Dr. Alan Chodos; Elizabeth A. Rogan
Nonlinear transmission of CO{sub 2} laser radiation by graphene
Science Conference Proceedings (OSTI)
The nonlinear transmission of multilayer ({approx}12 layers) graphene at the wavelength {lambda} {approx} 10 {mu}m is measured for the first time. The absorption saturation intensity in graphene ({approx}330 kW cm{sup -2}) and the ablation threshold of its outer layers ({approx}1 MW cm{sup -2}, 0.11 J cm{sup -2}) under action of a CO{sub 2} laser pulse with a duration of 70 - 85 ns at {lambda} = 10.55 {mu}m are determined. The residual absorption of graphene at its partial saturation was 48 % of the initial value. This is significantly smaller than the value measured previously for samples with a close number of layers at {lambda} = 1.55 {mu}m (92.3 % - 93.8 %). It is shown that the ablation threshold of two graphene layers adjacent to the BaF{sub 2} substrate (after successive ablation of outer layers) exceeds 0.27 J cm{sup -2}. (nonlinear optical phenomena)
Sorochenko, V R; Obraztsova, Elena D; Rusakov, P S; Rybin, M G [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
Science Conference Proceedings (OSTI)
A one-dimensional snowpack model, a unique airmass identification scheme, and surface weather observations are used to investigate large ablation events in the central Appalachian Mountains of North America. Data from cooperative observing ...
Daniel J. Leathers; Daniel Graybeal; Thomas Mote; Andrew Grundstein; David Robinson
Nanocrystallization Reactions and Kinetics, Chemical Partitioning ...
Science Conference Proceedings (OSTI)
Primary nanocrystallization reactions and kinetics will be discussed for selected FeCo-based ... Search of Half-Metallic Heusler Alloys and their Applications to�...
Thermodynamic and Kinetic Simulation and Experimental Results ...
Science Conference Proceedings (OSTI)
Through the use of thermodynamic and kinetic modeling software, NETL has designed a systematic method that has been successfully developed to design an�...
Investigating Grain Boundary Structure-Kinetic Property ...
Science Conference Proceedings (OSTI)
Abstract Scope, Grain boundary energy landscapes contain all the information that is required to describe the kinetic behavior of grain boundaries (GBs).
Infrared Thermographic Study of Laser Ignition
Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet. The experimental apparatus used to make these observations is described. The temperature distributions recorded are shown to be in good agreement with those predicted by heat transfer theory. Heat content values calculated from the observed temperature distributions are used to calculate thermal and kinetic parameters for several samples. These values are found to be in reasonable agreement with theory.
Mohler, Jonathan H.; Chow, Charles T. S.
ORION laser target diagnostics
The ORION laser facility is one of the UK's premier laser facilities which became operational at AWE in 2010. Its primary mission is one of stockpile stewardship, ORION will extend the UK's experimental plasma physics capability to the high temperature, high density regime relevant to Atomic Weapons Establishment's (AWE) program. The ORION laser combines ten laser beams operating in the ns regime with two sub ps short pulse chirped pulse amplification beams. This gives the UK a unique combined long pulse/short pulse laser capability which is not only available to AWE personnel but also gives access to our international partners and visiting UK academia. The ORION laser facility is equipped with a comprehensive suite of some 45 diagnostics covering optical, particle, and x-ray diagnostics all able to image the laser target interaction point. This paper focuses on a small selection of these diagnostics.
Bentley, C. D.; Edwards, R. D.; Andrew, J. E.; James, S. F.; Gardner, M. D.; Comley, A. J.; Vaughan, K.; Horsfield, C. J.; Rubery, M. S.; Rothman, S. D.; Daykin, S.; Masoero, S. J.; Palmer, J. B.; Meadowcroft, A. L.; Williams, B. M.; Gumbrell, E. T.; Fyrth, J. D.; Brown, C. R. D.; Hill, M. P.; Oades, K. [Plasma Physics Department, Atomic Weapons Establishment, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); and others
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ATF Laser Safety ATF Laser Safety To be present in a secured laser area at ATF, a person must either have the required laser training, or be continuously escorted by someone who has such training: The training consists of an eye exam, BNL general laser safety lecture, and formal ATF laser familiarization. Untrained personnel should not be instructed to enter interlocked areas or be escorted into an area and left unattended. If someone without training must enter a secured area, they must be continuously escorted, and are considered spectators, which means they may not perform any work in the area. At ATF, there are 3 classes of personnel authorized to enter secured areas: Experimental operators may secure areas, perform approved experiments with beams from facility lasers (YAG + CO2) or FEL beams, and
Numerical predictions of railgun performance including the effects of ablation and arc drag
Thermal radiation from plasma armatures in railguns may cause vaporization and partial ionization of the rail and insulator materials. This causes an increase in mass of the arc, which has an adverse effect on projectile velocity. Viscous drag on the arc also has a deleterious effect, particularly at high velocities. These loss mechanisms are modeled in the Los Alamos Railgun Estimator code. Simulations were performed and numerical results were compared with experimental data for a wide range of tests performed at the Los Alamos and Lawrence Livermore National Laboratories, the Ling Temco Vought Aerospace and Defense Company, and the Center for Electromechanics at the University of Texas at Austin. The effects of ablation and arc drag on railgun performance are discussed. Parametric studies illustrate the effects of some design parameters on projectile velocity and launcher efficiency. Some strategies for reducing the effects of ablation are proposed.
Schnurr, N.M.; Kerrisk, J.F.; Parker, J.V.
1D Scaling with Ablation for K-Shell Radiation from Stainless Steel Wire Arrays
Science Conference Proceedings (OSTI)
A 1D Lagrangian magnetohydrodynamic z-pinch simulation code is extended to include wire ablation. The plasma transport coefficients are calibrated to reproduce the K-shell yields measured on the Z generator for three stainless steel arrays of diameter 55 mm and masses ranging from 1.8 to 2.7 mg. The resulting 1D scaling model is applied to a larger SS array (65 mm and 2.5 mg) on the refurbished Z machine. Simulation results predict a maximum K-shell yield of 77 kJ for an 82 kV charging voltage. This maximum drops to 42 kJ at 75 kV charging. Neglecting the ablation precursor leads to a {approx}10% change in the calculated yield.
Giuliani, J. L.; Thornhill, J. W.; Dasgupta, A.; Davis, J. [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States); Clark, R. W. [Berkeley Research Associates, Beltsville Maryland 20705 (United States); Jones, B.; Cuneo, M.; Coverdale, C. A. [Sandia National Laboratories, Albuquerque NM 87545 (United States); Deeney, C. [National Nuclear Security Administration, Washington DC 20585 (United States)
Formation of jet-like spikes from the ablative Rayleigh-Taylor instability
Science Conference Proceedings (OSTI)
The mechanism of jet-like spike formation from the ablative Rayleigh-Taylor instability (ARTI) in the presence of preheating is reported. It is found that the preheating plays an essential role in the formation of the jet-like spikes. In the early stage, the preheating significantly increases the plasma density gradient, which can reduce the linear growth of ARTI and suppress its harmonics. In the middle stage, the preheating can markedly increase the vorticity convection and effectively reduce the vorticity intensity resulting in a broadened velocity shear layer near the spikes. Then the growth of ablative Kelvin-Helmholtz instability is dramatically suppressed and the ARTI remains dominant. In the late stage, nonlinear bubble acceleration further elongates the bubble-spike amplitude and eventually leads to the formation of jet-like spikes.
Wang, L. F.; Ye, W. H.; He, X. T. [HEDPS and CAPT, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Zhang, W. Y. [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Sheng, Z. M. [Key Laboratory for Laser Plasmas (MoE) and Department of Physics, Shanghai Jiaotong University, Shanghai 200240 (China); Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Yu, M. Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, Bochum D-44780 (Germany)
This report covers the fiscal year 1999 portion of our ongoing project to develop tracer spectral diagnostics of ablator conditions in the hohlraum radiation environment. The overall goal of the experimental campaign is to measure the turn-on times of K{sub a} absorption features from tracers buried in planar witness plates. The tracers are thin and at a specific, known depth in the witness plates so that the turn-on times are indicators of the arrival of the Marshak wave at the specified depths. Ultimately, we intend to compare the delay in the turn-on times of the tracer signals between doped and undoped ablator materials, and thus study the effect of ablator dopants on the Marshak wave velocity. During FY 1999, our primary goal was to simply measure an absorption signal, matching tracer depth to drive temperature and testing the overall feasibility of our experimental scheme. In indirect-drive inertial confinement fusion (ICF) energy is deposited rapidly on the outside of a spherical capsule, ablating the outer layers of the capsule and compressing the interior. If this process is carefully controlled, then hydrogen fuel at the center of the capsule can be compressed and heated such that fusion reactions may proceed. The efficiency of the compression depends crucially on the time-dependent energy deposition onto the ablator material on the outside of the capsule. The nature of this coupling can be controlled through the use of ablator dopants, which modify the density and opacity of the ablator layer. Clearly, it is crucial to the success of indirect-drive ICF to have a means for testing the effects of ablator dopants, and more generally for having a diagnostic that is capable of determining time-dependent ablator properties. To this end, we are adapting tracer spectroscopy techniques to make time-dependent measurements of the ionization state of planar ablator materials mounted on the sides of hohlraums. Specifically, we are doing backlighter point-projection spectroscopy of K{sub a} features from tracers placed in the interiors of planar witness plates made of ablator materials. As the radiation wave, or Marshak wave, diffuses into the ablator material it drives a shock ahead of it. When the shock arrives at a given point in the witness plate it heats the tracer to roughly 20 eV. Soon after, the radiation wave arrives, heating the tracer to well above 100 eV nearly instantaneously. Thus, the ''turn-on'' of tracer absorption from high ionization states is an indicator that the radiation wave has arrived at the tracer. Furthermore, the time-dependent ionization balance in the tracer is, our simulations show, indicative of the efficiency with which the radiation field couples to the ablator material. Note that this technique holds out the possibility of making a determination of the instantaneous impact of the radiation field on the ablator physics, as opposed to something like a shock breakout measurement, in which the observed signal reflects the integrated time-history of the impact of the radiation field on the ablator.
Cohen, David H.; MacFarlane, Joseph J.; Wang, Ping; Jaanimagi, Paul A.; Oertel, John; Magelssen, Glenn; Landen, Otto L.; Back, Christina A.; Olson, Richard E.; Bailey, James E.
Laser system using ultra-short laser pulses
A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.
Dantus, Marcos (Okemos, MI); Lozovoy, Vadim V. (Okemos, MI); Comstock, Matthew (Milford, MI)
spectra were analyzed with an effective Hamiltonian, and rotational, electric quadrupole Cu and D reagents have widespread usage in or- ganic chemistry.1 These compounds have many desirable synthetic
Ziurys, Lucy M.
by the Office of Environmental Waste Management and OfficeOffice of Basic Energy Science, Chemical Science Division and by the Environmental Management
Chan, George C.-Y.; Chan, Wing-Tat; Mao, Xianglei; Russo, Richard E.
Experimental techniques for subnanosecond resolution of laser-launched plates and impact studies
Miniature laser-launched plates have applications in shock wave physics, studying dynamic properties of materials and can be used to generate experimental data in a manner similar to a laboratory gas gun for one-dimensional impact experiments. Laser-launched plates have the advantage of small size, low kinetic energy, and can be launched with ubiquitous laboratory lasers. Because of the small size and high accelerations (10{sup 7}--10{sup 10} g`s), improved temporal resolution and optical non-contact methods to collect data are required. Traditional mechanical in-situ gauges would significantly impair the data quality and do not have the required time response.
Paisley, D.L.; Warnes, R.H.; Stahl, D.B. [Los Alamos National Lab., NM (United States). Dynamic Experimentation Div.
Chemical kinetics and oil shale process design
Oil shale processes are reviewed with the goal of showing how chemical kinetics influences the design and operation of different processes for different types of oil shale. Reaction kinetics are presented for organic pyrolysis, carbon combustion, carbonate decomposition, and sulfur and nitrogen reactions.
Burnham, A.K.
ERNSTMORITZARNDTUNIVERSITAT Absolute number density and kinetic analysis
plasma-chemical reactions. Therefore, from the analysis of their kinetics, one can learn more about of the technical applications, many plasmachemical processes within the discharges as well as mechanisms determines all electron induced plasma-chemical processes and hence influences the kinetics of species
Greifswald, Ernst-Moritz-Arndt-Universität
Kinetics of Enzymatic Depolymerization of Guar Galactomannan
is used as a rheology modifier in many of its applications, previous kinetic studies have been limitedKinetics of Enzymatic Depolymerization of Guar Galactomannan Shamsheer Mahammad, Robert K. Prud'homme, George W. Roberts,*, and Saad A. Khan*, Department of Chemical and Biomolecular Engineering, North
Khan, Saad A.
Kinetic advantage of controlled intermediate nuclear fusion
The dominated process of controlled fusion is to let nuclei gain enough kinetic energy to overcome Coulomb barrier. As a result, a fusion scheme can consider two factors in its design: to increase kinetic energy of nuclei and to alter the Coulomb barrier. Cold Fusion and Hot fusion are all one-factor schemes while Intermediate Fusion is a twofactors scheme. This made CINF kinetically superior. Cold Fusion reduces deuteron-deuteron distance, addressing Coulomb barrier, and Hot Fusion heat up plasma into extreme high temperature, addressing kinetic energy. Without enough kinetic energy made Cold Fusion skeptical. Extreme high temperature made Hot Fusion very difficult to engineer. Because CIFN addresses both factors, CIFN is a more promising technique to be industrialized.
Guo Xiaoming [Physics and Computer Science Department, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5 (Canada)
Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes
Design considerations for a laser-plasma linear collider,"E.Esarey, and W.P.Leemans, "Free-electron laser driven bythe LBNL laser-plasma accelerator," in Proc. Adv. Acc. Con.
Geddes, C.G.R.
A laser medium is particularly useful in high average power solid state lasers. The laser medium includes a chromium dopant and preferably neodymium ions as codopant, and is primarily a gadolinium scandium gallium garnet, or an analog thereof. Divalent cations inhibit spiral morphology as large boules from which the laser medium is derived are grown, and a source of ions convertible between a trivalent state and a tetravalent state at a low ionization energy are in the laser medium to reduce an absorption coefficient at about one micron wavelength otherwise caused by the divalent cations. These divalent cations and convertible ions are dispersed in the laser medium. Preferred convertible ions are provided from titanium or cerium sources.
Stokowski, S.E.
A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam.
Jassby, Daniel L. (Princeton, NJ)
Science Conference Proceedings (OSTI)
... powered down. 5. Close coolant valves, if chilled water is used; visually check for leaks. 6. Turn off the laser warning light.
Requirements for the LCLS injector drive laser present significant challenges to the design of the system. While progress has been demonstrated in spatial shape, temporal shape, UV generation and rep-rate, a laser that meets all of the LCLS specifications simultaneously has yet to be demonstrated. These challenges are compounded by the stability and reliability requirements. The drive laser and transport system has been installed and tested. We will report on the current operational state of the laser and plans for future improvements.
Dowell, D.H.; Castro, J.; Emma, P.; Frisch, J.; Gilevich, A.; Hays, G.; Hering, P.; Limborg-Deprey, C.; Loos, H.; Miahnahri, A.; White, W.; /SLAC
Robot Assisted Laser Osteotomy.
??In the scope of this thesis world's first robot system was developed, which facilitates osteotomy using laser in arbitrary geometries with an overall accuracy below� (more)
Burgner, Jessica
Electron acceleration & laser pulse compression using a laser...
NLE Websites -- All DOE Office Websites (Extended Search)
acceleration & laser pulse compression using a laser-plasma accelerator Wednesday, August 14, 2013 - 3:00pm SLAC, Redtail Hawk Conference Room 108A Andreas Walker, Oxford...
Laser Program annual report 1987
This report discusses the following topics: target design and experiments; target materials development; laboratory x-ray lasers; laser science and technology; high-average-power solid state lasers; and ICF applications studies.
O'Neal, E.M.; Murphy, P.W.; Canada, J.A.; Kirvel, R.D.; Peck, T.; Price, M.E.; Prono, J.K.; Reid, S.G.; Wallerstein, L.; Wright, T.W. (eds.)
NLE Websites -- All DOE Office Websites (Extended Search)
Nd:YAG Laser The Nd:YAG laser is located in a class 1000 clean room (the YAG Room) near the electron gun end of the ATF accelerator. The clean area also includes a separate laser...
BNL | CFN Laser System Qualifications
NLE Websites -- All DOE Office Websites (Extended Search)
System Qualification There are multiple laser systems at the CFN. Users who will work with the following class 3b or 4 laser systems are required to complete the Laser Safety...
Model simplification of chemical kinetic systems under uncertainty
This thesis investigates the impact of uncertainty on the reduction and simplification of chemical kinetics mechanisms. Chemical kinetics simulations of complex fuels are very computationally expensive, especially when ...
Coles, Thomas Michael Kyte
Modeling of Reactor Kinetics and Dynamics
In order to model a full fuel cycle in a nuclear reactor, it is necessary to simulate the short time-scale kinetic behavior of the reactor as well as the long time-scale dynamics that occur with fuel burnup. The former is modeled using the point kinetics equations, while the latter is modeled by coupling fuel burnup equations with the kinetics equations. When the equations are solved simultaneously with a nonlinear equation solver, the end result is a code with the unique capability of modeling transients at any time during a fuel cycle.
Matthew Johnson; Scott Lucas; Pavel Tsvetkov
Laser ultrasonics on moving paper
NLE Websites -- All DOE Office Websites (Extended Search)
Laser ultrasonics on moving paper Title Laser ultrasonics on moving paper Publication Type Journal Article LBNL Report Number LBNL-43615 Year of Publication 1999 Authors Ridgway,...
Laser Power and Energy Calibrations
Science Conference Proceedings (OSTI)
... calibration services for meters used with the lasers, wavelengths, and power ranges shown in the following table. Other laser wavelengths, power ...
Optimizing the treatment of breast cancer remains a major topic of interest. In current clinical practice, breast-conserving therapy is the standard of care for patients with localized breast cancer. Technological developments have fueled interest in less invasive breast cancer treatment. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a completely noninvasive ablation technique. Focused beams of ultrasound are used for ablation of the target lesion without disrupting the skin and subcutaneous tissues in the beam path. MRI is an excellent imaging method for tumor targeting, treatment monitoring, and evaluation of treatment results. The combination of HIFU and MR imaging offers an opportunity for image-guided ablation of breast cancer. Previous studies of MR-HIFU in breast cancer patients reported a limited efficacy, which hampered the clinical translation of this technique. These prior studies were performed without an MR-HIFU system specifically developed for breast cancer treatment. In this article, a novel and dedicated MR-HIFU breast platform is presented. This system has been designed for safe and effective MR-HIFU ablation of breast cancer. Furthermore, both clinical and technical challenges are discussed, which have to be solved before MR-HIFU ablation of breast cancer can be implemented in routine clinical practice.
Merckel, Laura G., E-mail: email@example.com [University Medical Center Utrecht, Department of Radiology (Netherlands); Bartels, Lambertus W., E-mail: firstname.lastname@example.com [University Medical Center Utrecht, Image Sciences Institute (Netherlands); Koehler, Max O., E-mail: email@example.com [Philips Healthcare (Finland); Bongard, H. J. G. Desiree van den, E-mail: email@example.com [University Medical Center Utrecht, Department of Radiotherapy (Netherlands); Deckers, Roel, E-mail: email@example.com [University Medical Center Utrecht, Image Sciences Institute (Netherlands)] [University Medical Center Utrecht, Image Sciences Institute (Netherlands); Mali, Willem P. Th. M., E-mail: email@example.com [University Medical Center Utrecht, Department of Radiology (Netherlands); Binkert, Christoph A., E-mail: email@example.com [Cantonal Hospital Winterthur, Department of Radiology (Switzerland); Moonen, Chrit T., E-mail: email@example.com [University Medical Center Utrecht, Image Sciences Institute (Netherlands); Gilhuijs, Kenneth G. A., E-mail: firstname.lastname@example.com; Bosch, Maurice A. A. J. van den, E-mail: email@example.com [University Medical Center Utrecht, Department of Radiology (Netherlands)
Indium tin oxide (ITO) nanostructures were successfully deposited on glass substrate by pulsed laser ablation in argon gas at 250 deg. C. Microstructural changes were observed in the argon gas pressure between 30 to 50 mTorr. The as-grown, nanostructured ITO exhibit In{sub 2}O{sub 3} bixbyite structure orientated at <111> direction. At the initial stage of growth, there was a large number of nucleation sites detected which eventually evolved into needle-like branches. The presence of spheres at the tip of these branches indicates that these nanostructured ITO were likely governed by vapor-liquid-solid (VLS) growth mechanism.
Tan, S. S.; Lee, W. K.; Kee, Y. Y.; Wong, H. Y.; Tou, T. Y. [Faculty of Engineering, Multimedia University, 63100 Cyberjaya (Malaysia)
An improved dye laser amplifier is disclosed. The efficiency of the dye laser amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant. 3 figs.
Moses, E.I.
The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.
Comaskey, Brian J. (Walnut Creek, CA); Scheibner, Karl F. (Tracy, CA); Ault, Earl R. (Livermore, CA)
This invention relates to a laser system of rugged design suitable for use in a field environment. The laser itself is of coaxial design with a solid potting material filling the space between components. A reservoir is employed to provide a gas lasing medium between an electrode pair, each of which is connected to one of the coaxial conductors. (auth)
Nelson, M.A.; Davies, T.J.
Explosively pumped laser light
A single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.
Piltch, Martin S. (Los Alamos, NM); Michelotti, Roy A. (Los Alamos, NM)
Laser beam generating apparatus
Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 11 figures.
Warner, B.E.; Duncan, D.B.
Laser beam generating apparatus
Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).
Warner, Bruce E. (Livermore, CA); Duncan, David B. (Auburn, CA)
Laser beam generating apparatus
Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus is described. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect). 7 figures.
Warner, B.E.; Duncan, D.B.
Laser beam generating apparatus
Laser beam generating apparatus including a septum segment disposed longitudinally within the tubular structure of the apparatus. The septum provides for radiatively dissipating heat buildup within the tubular structure and for generating relatively uniform laser beam pulses so as to minimize or eliminate radial pulse delays (the chevron effect).
Warner, Bruce E. (Livermore, CA); Duncan, David B. (Auburn, CA)
Rainfall Kinetic Energy in Eastern Australia
Science Conference Proceedings (OSTI)
Rainfall kinetic energy is a commonly used climatic parameter for the prediction of soil erosion by water. Such a parameter is difficult to measure and is usually estimated from relationships established between rainfall energy and rainfall ...
Colin John Rosewell
Kinetic Energy LLC | Open Energy Information
Name Kinetic Energy LLC Place Texas Utility Id 56210 Utility Location Yes Ownership R NERC ERCOT Yes ISO Ercot Yes Activity Retail Marketing Yes References EIA Form EIA-861...
AER NY Kinetics LLC | Open Energy Information
Database. This company is involved in the following MHK Projects: Ogdensburg Kinetic Energy Project This article is a stub. You can help OpenEI by expanding it. Retrieved...
Radiofrequency Thermal Ablation: Increase in Lesion Diameter with Continuous Acetic Acid Infusion
Purpose. To evaluate the influence of continuous infusion of acetic acid 50% during radiofrequency ablation (RFA) on the size of the thermal lesion produced. Methods. Radiofrequency (RF) was applied to excised bovine liver by using an expandable needle electrode with 10 retractable tines (LeVeen Needle Electrode, RadioTherapeutics, Sunnyvale, CA) connected to a commercially available RF generator (RF 2000, RadioTherapeutics, Sunnyvale, CA). Experiments were performed using three different treatment modalities: RF only (n = 15), RF with continuous saline 0.9% infusion (n = 15), and RF with continuous acetic acid 50% infusion (n = 15). RF duration, power output, tissue impedance, and time to a rapid rise in impedance were recorded. The ablated lesions were evaluated both macroscopically and histologically. Results. The ablated lesions appeared as spherical or ellipsoid, well-demarcated pale areas with a surrounding brown rim with both RF only and RF plus saline 0.9% infusion. In contrast, thermolesions generated with RF in combination with acetic acid 50% infusion were irregular in shape and the central portion was jelly-like. Mean diameter of the coagulation necrosis was 22.3 {+-} 2.1 mm (RF only), 29.2 {+-} 4.8 mm (RF + saline 0.9%) and 30.7 {+-} 5.7 mm (RF + acetic acid 50%), with a significant increase in the RF plus saline 0.9% and RF plus acetic acid 50% groups compared with RF alone. Time to a rapid rise in impedance was significantly prolonged in the RF plus saline 0.9% and RF plus acetic acid 50% groups compared with RF alone. Conclusions. A combination of RF plus acetic acid 50% infusion is able to generate larger thermolesions than RF only or RF combined with saline 0.9% infusion.
Lubienski, Andreas [Ruprecht-Karls-University Heidelberg, Department of Diagnostic Radiology (Germany)], E-mail: firstname.lastname@example.com; Duex, Markus [Hospital Northwest Frankfurt, Department of Radiology (Germany); Lubienski, Katrin; Grenacher, Lars; Kauffmann, Guenter [Ruprecht-Karls-University Heidelberg, Department of Diagnostic Radiology (Germany)
A laser beam dividing apparatus (10) having a first beam splitter (14) with an aperture (16) therein positioned in the path of a laser beam (12) such that a portion of the laser beam (12) passes through the aperture (16) onto a second beam splitter (20) and a portion of the laser beam (12) impinges upon the first beam splitter (14). Both the first beam splitter (14) and the second beam splitter (20) are, optionally, made from a dichroic material such that a green component (24) of the laser beam (12) is reflected therefrom and a yellow component (26) is refracted therethrough. The first beam splitter (14) and the second beam splitter (20) further each have a plurality of facets (22) such that the components (24, 26) are reflected and refracted in a number equaling the number of facets (22).
English, Jr., R. Edward (Tracy, CA); Johnson, Steve A. (Tracy, CA)
A catalac free electron laser using a rf linac (catalac) which acts as a catalyst to accelerate an electron beam in an initial pass through the catalac and decelerate the electron beam during a second pass through the catalac is described. During the second pass through the catalac, energy is extracted from the electron beam and transformed to energy of the accelerating fields of the catalac to increase efficiency of the device. Various embodiments disclose the use of post linacs to add electron beam energy extracted by the wiggler and the use of supplementary catalacs to extract energy at various energy peaks produced by the free electron laser wiggler to further enhance efficiency of the catalac free electron laser. The catalac free electron laser can be used in conjunction with a simple resonator, a ring resonator, or as an amplifier in conjunction with a master oscillator laser.
Brau, C.A.; Swenson, D.A.; Boyd, T.J. Jr.
A catalac free electron laser using a rf linac (catalac) which acts as a catalyst to accelerate an electron beam in an initial pass through the catalac and decelerate the electron beam during a second pass through the catalac. During the second pass through the catalac, energy is extracted from the electron beam and transformed to energy of the accelerating fields of the catalac to increase efficiency of the device. Various embodiments disclose the use of post linacs to add electron beam energy extracted by the wiggler and the use of supplementary catalacs to extract energy at various energy peaks produced by the free electron laser wiggler to further enhance efficiency of the catalac free electron laser. The catalac free electron laser can be used in conjunction with a simple resonator, a ring resonator or as an amplifier in conjunction with a master oscillator laser.
Brau, Charles A. (Los Alamos, NM); Swenson, Donald A. (Los Alamos, NM); Boyd, Jr., Thomas J. (Los Alamos, NM)
Laser controlled flame stabilization
A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.
Early, James W. (Los Alamos, NM); Thomas, Matthew E. (Huntsville, AL)
Laser damage of optical materials, first reported in 1964, continues to limit the output energy and power of pulsed and continuous-wave laser systems. In spite of some 48 years of research in this area, interest from the international laser community to laser damage issues remains at a very high level and does not show any sign of decreasing. Moreover, it grows with the development of novel laser systems, for example, ultrafast and short-wavelength lasers that involve new damage effects and specific mechanisms not studied before. This interest is evident from the high level of attendance and presentations at the annual SPIE Laser Damage Symposium (aka, Boulder Damage Symposium) that has been held in Boulder, Colorado, since 1969. This special section of Optical Engineering is the first one devoted to the entire field of laser damage rather than to a specific part. It is prepared in response to growing interest from the international laser-damage community. Some papers in this special section were presented at the Laser Damage Symposium; others were submitted in response to the general call for papers for this special section. The 18 papers compiled into this special section represent many sides of the broad field of laser-damage research. They consider theoretical studies of the fundamental mechanisms of laser damage including laser-driven electron dynamics in solids (O. Brenk and B. Rethfeld; A. Nikiforov, A. Epifanov, and S. Garnov; T. Apostolova et al.), modeling of propagation effects for ultrashort high-intensity laser pulses (J. Gulley), an overview of mechanisms of inclusion-induced damage (M. Koldunov and A. Manenkov), the formation of specific periodic ripples on a metal surface by femtosecond laser pulses (M. Ahsan and M. Lee), and the laser-plasma effects on damage in glass (Y. Li et al). Material characterization is represented by the papers devoted to accurate and reliable measurements of absorption with special emphasis on thin films (C. M�hlig and S. Bublitz; B. Cho, E. Danielewicz, and J. Rudisill; W. Palm et al; and J. Lu et al.). Statistical treatment of measurements of the laser-damage threshold (J. Arenberg) and the relationship to damage mechanisms (F. Wagner et al.) represent the large subfield of laser-damage measurements. Various aspects of multilayer coating and thin-film characterization are considered in papers by B. Cho, J. Rudisill, and E. Danielewicz (spectral shift in multilayer mirrors) and R. Weber et al. (novel approach to damage studies based on third-harmonic generation microscopy). Of special interest for readers is the paper by C. Stolz that summarizes the results of four �thin-film damage competitions� organized as a part of the Laser Damage Symposium. Another paper is devoted to thermal annealing of damage precursors (N. Shen et al.). Finally, the influence of nano-size contamination on initiation of laser damage by ultrashort pulses is considered in paper of V. Komolov et al.
Vitaly Gruzdev, Michelle D. Shinn
Kinetic Energy and the Equivalence Principle
According to the general theory of relativity, kinetic energy contributes to gravitational mass. Surprisingly, the observational evidence for this prediction does not seem to be discussed in the literature. I reanalyze existing experimental data to test the equivalence principle for the kinetic energy of atomic electrons, and show that fairly strong limits on possible violations can be obtained. I discuss the relationship of this result to the occasional claim that ``light falls with twice the acceleration of ordinary matter.''
S. Carlip
Micro-Raman spectroscopy has been applied to investigate the impact of laser irradiation on semiconducting CdTe/ZnTe quantum dots (QDs) structures. A reference sample (without dots) was also studied for comparison. Both samples were grown by molecular beam epitaxy technique on the p-type GaAs substrate. The Raman spectra have been recorded for different time of a laser exposure and for various laser powers. The spectra for both samples exhibit peak related to the localized longitudinal (LO) ZnTe phonon of a wavenumber equal to 210 cm{sup -1}. For the QD sample, a broad band corresponding to the LO CdTe phonon related to the QD-layer appears at a wavenumber of 160 cm{sup -1}. With increasing time of a laser beam exposure and laser power, the spectra get dominated by tellurium-related peaks appearing at wavenumbers around 120 cm{sup -1} and 140 cm{sup -1}. Simultaneously, the ZnTe surface undergoes rising damage, with the formation of Te aggregates at the pinhole edge as reveal atomic force microscopy observations. Local temperature of irradiated region has been estimated from the anti-Stokes/Stokes ratio of the Te modes intensity and it was found to be close or exceeding ZnTe melting point. Thus, the laser damage can be explained by the ablation process.
Zielony, E.; Placzek-Popko, E.; Henrykowski, A.; Gumienny, Z.; Kamyczek, P.; Jacak, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Nowakowski, P.; Karczewski, G. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw (Poland)
Free electron laser designs for laser amplification
Method for laser beam amplification by means of free electron laser techniques. With wiggler magnetic field strength B.sub.w and wavelength .lambda..sub.w =2.pi./k.sub.w regarded as variable parameters, the method(s) impose conditions such as substantial constancy of B.sub.w /k.sub.w or k.sub.w or B.sub.w and k.sub.w (alternating), coupled with a choice of either constant resonant phase angle or programmed phase space "bucket" area.
Prosnitz, Donald (Walnut Creek, CA); Szoke, Abraham (Fremont, CA)
Design of a streaked radiography instrument for ICF ablator tuning measurements
A streaked radiography diagnostic has been proposed as a technique to determine the ablator mass remaining in an inertial confinement fusion ignition capsule at peak velocity. This instrument, the 'HXRI-5', has been designed to fit within a National Ignition Facility Diagnostic Instrument Manipulator. The HXRI-5 will be built at Sandia National Laboratories (SNL), and initial testing will be done at the SNL Z-Beamlet Facility. In this paper, we will describe the National Ignition Campaign requirements for this diagnostic, the instrument design, and the planned test experiments.
Olson, R. E.; Geissel, M.; Kellogg, J. W.; Bennett, G. R.; Edens, A. D.; Atherton, B. W.; Leeper, R. J. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Hicks, D. G.; Spears, B. K.; Celliers, P. M.; Holder, J. P.; Landen, O. L. [Lawrence Livermore National Laboratories, Livermore, California 94550 (United States)
Science Conference Proceedings (OSTI)
This is an annual report covering research progress on laser fusion and the OMEGA Upgrade design and development. In laser fusion, line-spectroscopy methods were demonstrated to be useful in diagnosing the core temperature and densities of polymer-shell targets; a theoretical analysis of nonlocal heat transport effects on filamentation of light in plasmas confirms that the principle mechanism driving filamentation is kinetic thermal rather than ponderomotive; a new method (spatial beam deflection) to produce laser pulses of arbitrary shape was developed; laser-plasma x-ray emission was measured using photodiode arrays; experiments on long-scale-length plasmas have shown that smoothing by spectral dispersion has proven effective in reducing Raman scattering; a method for increasing the gas-retention time of polymer shell targets was developed by overcoating them with aluminum. Experiments relating to the OMEGA Upgrade are described.
Not Available
A general kinetic model: Kinetics and atomic-scale mechanisms of feldspar dissolution.
??This thesis presents a general kinetic model and its application to feldspar dissolution. In the framework of Monte Carlo methods, the model simulates the stochastic� (more)
Zhang, Li
instruments applied to analysis of complex chemical mixturesrelies on chemical separation (by chromatography) into pureThe multiplexed chemical kinetic photoionization mass
Osborne, David L.
Kinetic Theory of Plasma Waves - Part III: Inhomogeneous Plasma
Science Conference Proceedings (OSTI)
Kinetic Theory / Proceedings of the Ninth Carolus Magnus Summer School on Plasma and Fusion Energy Physics
P. U. Lamalle
Kinetic Theory of Plasma Waves - Part I: Introduction
Science Conference Proceedings (OSTI)
Kinetic Theory / Proceedings of the Ninth Carolus Magnus Summer School on Plasma and Fusion Energy Physics
P. U. Lamalle
Quantum electrodynamics in a laser and the electron laser collision
Quantum electrodynamics in a laser is formulated, in which the electron-laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron-laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of $\\gamma-$ray laser generation by use of this kind of collision is discussed.
Qi-Ren Zhang
Photo-oxidation of Ge Nanocrystals: Kinetic Measurements by InSitu Raman Spectroscopy
Ge nanocrystals are formed in silica by ion beam synthesis and are subsequently exposed by selective HF etching of the silica. Under ambient conditions, the exposed nanocrystals are stable after formation of a protective native oxide shell of no more than a few monolayers. However, under visible laser illumination at room temperature and in the presence of O{sub 2}, the nanocrystals rapidly oxidize. The oxidation rate was monitored by measuring the Raman spectra of the Ge nanocrystals in-situ. The intensity ratio of the anti-Stokes to the Stokes line indicated that no significant laser-induced heating of illuminated nanocrystals occurs. Therefore, the oxidation reaction rate enhancement is due to a photo-chemical process. The oxidation rate varies nearly linearly with the logarithm of the laser intensity, and at constant laser intensity the rate increases with increasing photon energy. These kinetic measurements, along with the power dependencies, are described quantitatively by an electron active oxidation mechanism involving tunneling of optically excited electrons through the forming oxide skin and subsequent transport of oxygen ions to the Ge nanocrystal surface.
Sharp, I.D.; Xu, Q.; Yuan, C.W.; Beeman, J.W.; Ager III, J.W.; Chrzan, D.C.; Haller, E.E.
1982 laser program annual report
Science Conference Proceedings (OSTI)
This annual report covers the following eight sections: (1) laser program review, (2) laser systems and operation, (3) target design, (4) target fabrication, (5) fusion experiments program, (6) Zeus laser project, (7) laser research and development, and (8) energy applications. (MOW)
Hendricks, C.D.; Grow, G.R. (eds.)
A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.
Erickson, G.F.
Science Conference Proceedings (OSTI)
To meet the ignition system needs of large bore high pressure lean burn natural gas engines a laser diode side pumped passively Q-switched laser igniter was designed and tested. The laser was designed to produce the optical intensities needed to initiate ignition in a lean burn high brake mean effective pressure (BMEP) engine. The experimentation explored a variety of optical and electrical input parameters that when combined produced a robust spark in air. The results show peak power levels exceeding 2 MW and peak focal intensities above 400 GW/cm2. Future research avenues and current progress with the initial prototype are presented and discussed.
McIntyre, D.L.; Richardson, S.W.; Woodruff, S.D.; McMillian, M.H.; Guutam, M. (West Virginia Univ., Morgantown, WV)
PBX 9404 is an early formulation of HMX from which we can learn about the effects of aging in the weapons stockpile. Of particular interest is the presence of 3% nitrocellulose in PBX 9404 as an energetic binder. Nitrocellulose is used pervasively in smokeless gunpowders and was formerly used extensively in the film and art preservation industries. It is well known that nitrocellulose decomposes autocatalytically, and stabilizers, such as the diphenylamine used in PBX 9404, are used to retard its decomposition. Even so, its lifetime is still limited, and the reactions eventually leading to catastrophic autocatalysis are still not understood well despite years of work. In addition to reducing the available energy in the explosive, degradation of nitrocellulose affects the mechanical properties of the pressed PBX 9404 parts by the associated reduction in molecular weight, which reduces the strength of the binder. A structural formula for a monomer of the nitrocellulose used in PBX 9404 is shown. The initial nitration level is 2.3 of 3.0 possible sites, and they have different reactivities. Degradation of nitrocellulose affects many properties. As an aid in examining historical chemical analysis data, several measures of degradation are given for the simple replacement of a nitro group with a hydrogen. The weight percent of nitrocellulose remaining for an initial concentration of 3% as used in PBX 9404 is also given. Of course, the real degradation reaction is more complicated, including chain scission and crosslinking reactions giving other gas species. During the course of this work, we spent considerable time addressing the question, ''Why is PBX 9404 blue?'' There was actually considerable controversy in the color evolution with aging, and the situation was clarified by Ben Richardson at Pantex. Workers there assured us that PBX 9404 starts with an ivory color. Drying the prill prior to pressing turns it a mottled blue, and well-preserved prill samples retain a blue color decades after formulation. Subsequently, heat and light both send it through a progression of colors from grayish blue, blue-green, green, brown, dirty yellow, mottled tan, and eventually pale tan. The progression is accelerated by oxygen and possibly moisture, as has been shown in several accelerated aging studies. The precise compounds causing the color evolution are uncertain, but they are undoubtedly a progression of quinoidal, nitroso, and nitrated DPA compounds. For example, paranitroso DPA is deep blue. Unfortunately, the location of various nitrated DPAs, which ranged from yellow to orange to red to brown and which were used by Pantex as analytical standards in the 1970s, is not currently known. While the color change is indicative of aging, it is by no means a quantitative measure of the extent of nitrocellulose degradation. Inspection of the literature yielded a variety of kinetic models, and the activation energy typically ranges from 25-35 kcal/mol for T<100 C. This literature qualitatively predicts times for 30% decomposition ranging from a few days at 100 C to 1-2 years at 50 C to 50 years at room temperature. To develop a quantitative model, we used the data of Leider and Seaton, which were collected at conditions most closely matching stockpile conditions for any data set we had available. They used PBX 9404 heated as pressed pellets in closed vessels at temperatures ranging from 50 to 100 C for times up to three years, and they report mass loss, gas yield and composition, and chemical analysis of the residual solid by methods used in stockpile surveillance. Initial kinetic analysis of the weight of remaining nitrocellulose as measured by liquid chromatography and the loss of nitrate esters by a colorimetric technique gave an activation energy of 27 kcal/mol. However, the reaction is complex due to the different stability of the three nitroester positions, and this complexity required either parallel first-order reactions or an nth-order reaction (n=3.6), which is mathematically equivalent to a Gamma distribution of frequency factors
Burnham, A K; Fried, L E
Science Conference Proceedings (OSTI)
It is well known that for increasingly rarefied flowfields, the predictions from continuum formulation, such as the Navier-Stokes equations lose accuracy. For the high speed diatomic molecular flow in the transitional regime, the inaccuracies are partially ... Keywords: Gas-kinetic method, Hypersonic and rarefied flows, Multiple temperature kinetic model
Kun Xu; Xin He; Chunpei Cai
Computational Modeling and Real-Time Control of Patient-Specific Laser Treatment of Cancer
Abstract�An adaptive feedback control system is presented which employs a computational model of bioheat transfer in living tissue to guide, in real-time, laser treatments of prostate cancer monitored by magnetic resonance thermal imaging. The system is built on what can be referred to as cyberinfrastructure�a complex structure of high-speed network, large-scale parallel computing devices, laser optics, imaging, visualizations, inverse-analysis algorithms, mesh generation, and control systems that guide laser therapy to optimally control the ablation of cancerous tissue. The computational system has been successfully tested on in vivo, canine prostate. Over the course of an 18 min laser-induced thermal therapy performed at M.D. Anderson Cancer Center (MDACC) in Houston, Texas, the computational models were calibrated to intra-operative real-time thermal imaging treatment data and the calibrated models controlled the bioheat transfer to within 5 �C of the predetermined treatment plan. The computational arena is in Austin, Texas and managed at the Institute for Computational Engineering and Sciences (ICES). The system is designed to control the bioheat transfer remotely while simultaneously providing real-time remote visualization of the on-going treatment. Post-operative histology of the canine prostate reveal that the damage region was within the targeted 1.2 cm diameter treatment objective. Keywords�Hyperthermia, Real-time computing, Medical imaging, Cancer treatment, Cyberinfrastructure, PDE
unknown authors
Chemical Kinetic Modeling of Advanced Transportation Fuels
Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.
PItz, W J; Westbrook, C K; Herbinet, O
Terahertz radiation from laser accelerated electron bunches
NUMBER 5 MAY 2004 Terahertz radiation from laser acceleratedand millimeter wave radiation from laser acceleratedNo. 5, May 2004 Terahertz radiation from laser accelerated
Laser Extinction in Laminar Inverse Diffusion Flames
Diagnostics, Chapter 9: Laser-Induced Incandescence,Laser Extinction in Laminar Inverse Diffusion Flames WesternFoundation, Arlington, VA Laser Extinction in Laminar
Macko, Kevin; Mikofski, Mark A; Fernandez-Pello, Carlos; Blevins, Linda G; Davis, Ronald W.
Energy.gov (U.S. Department of Energy (DOE))
Berkeley Lab Laser Accelerator (BELLA) Laser Acquisition, Installation and Use for Research and Development
A nuclear pumped laser capable of producing long pulses of very high power laser radiation is provided. A toroidal fusion reactor provides energetic neutrons which are slowed down by a moderator. The moderated neutrons are converted to energetic particles capable of pumping a lasing medium. The lasing medium is housed in an annular cell surrounding the reactor. The cell includes an annular reflecting mirror at the bottom and an annular output window at the top. A neutron reflector is disposed around the cell to reflect escaping neutrons back into the cell. The laser radiation from the annular window is focused onto a beam compactor which generates a single coherent output laser beam. 10 figs.
Jassby, D.L.
Terahertz quantum cascade lasers
The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) ...
Williams, Benjamin S. (Benjamin Stanford), 1974-
1984). Colson, W. B. , "Free electron laser theory," Ph.D.M. 0. , Spitzer, R. , editors, Free Electron Generators ofM.D. , Spitzer, R. , editors, Free Electron Generators of
Colson, W.B.
A discharge tube for a gaseous laser is terminated with windows made of crystalline quartz which do not fluoresce in the presence of high energy, visible and ultraviolet light radiation.
Alves, R.W.; Costich, V.R.
We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.
Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM
The disclosure relates to low loss, high power variable attenuators comprng one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength.
Foltyn, Stephen R. (Los Alamos, NM)
A pulsed gas laser is constituted by Blumlein circuits wherein space metal plates function both as capacitors and transmission lines coupling high frequency oscillations to a gas filled laser tube. The tube itself is formed by spaced metal side walls which function as connections to the electrodes to provide for a high frequency, high voltage discharge in the tube to cause the gas to lase. Also shown is a spark gap switch having structural features permitting a long life.
Anderson, Louis W. (Madison, WI); Fitzsimmons, William A. (Madison, WI)
The disclosure relates to low loss, high power variable attenuators comprising one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength. 9 figs.
Foltyn, S.R.
The properties of an improved class of lasers is presented. In one configuration of these lasers the radiation propagates radially within the amplifying medium, resulting in high fields and symmetric illumination at the resonator axis. Thus there is a strong focusing of energy at the axis of the resonator. In a second configuration the radiation propagates back and forth in a tubular region of space.
Casperson, Lee W. (Los Angeles, CA)
Laser Initiated Actuator study
The program task was to design and study a laser initiated actuator. The design of the actuator is described, it being comprised of the fiber and body subassemblies. The energy source for all experiments was a Spectra Diode 2200-H2 laser diode. The diode is directly coupled to a 100 micron core, 0.3 numerical aperture fiber optic terminated with an SMA connector. The successful testing results are described and recommendations are made.
Watson, B.
Kinetic effects on robustness of electron magnetohydrodynamic structures
Following recent remarkable progress in the development of high-power short-pulse lasers, exploration is ongoing into hitherto unknown phenomena at fast time scales of electrons, the understanding of which is becoming crucial. For a simplified description of such phenomena, the Electron Magnetohydrodynamics (EMHDs) fluid description is often adopted. For the possibility of electron transport in high-density plasma, exact solutions of the EMHD model in the form of electron vortex currents, together with their associated magnetic fields, have been considered. However, the fluid EMHD model does not incorporate kinetic effects. Here, the finite Larmor radius effects owing to a finite electron temperature on the robustness of the exact EMHD structures are investigated using two-dimensional particle-in-cell simulations. It is found that larger EMHD vortex structures can sustain themselves for long periods, even in high temperature plasma; however, sustaining structures at higher temperatures tends to be difficult. With increasing temperature, electrons with finite Larmor radii become disengaged from the localized region. It is also shown that structures localized in smaller regions are more difficult to sustain. A quantitative criterion in terms of the structure size and Larmor radius has been established by simulations over a wide range of parameters. Finally, we conclude that a structure, larger than about eight times the typical Larmor radius at r=R, could form and exist even under the effects of finite electron temperature.
Hata, M. [Department of Physics, Nagoya University, Nagoya 464-8603 (Japan); Sakagami, H. [Fundamental Physics Simulation Research Division, National Institute for Fusion Science, Toki 509-5292 (Japan); Das, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
CRC handbook of laser science and technology. Volume 3. Gas lasers
Science Conference Proceedings (OSTI)
This book describes the fundamentals of gas lasers. It provides information and data on neutral gas lasers, ionized gas lasers, and molecular gas lasers. Concluding this volume is an extensive table of all gas laser wavelengths.
Weber, M.J.
Free-electron laser driven by the LBNL laser-plasma accelerator
Free-electron laser driven by the LBNL laser-plasmaA design of a compact free-electron laser (FEL), generatingare considered. Keywords: Free-electron laser, laser-plasma
Schroeder, C. B.
Optimizing conversion efficiency and reducing ion energy in a laser-produced Gd plasma
Science Conference Proceedings (OSTI)
We have demonstrated an efficient extreme ultraviolet (EUV) source at 6.7 nm by irradiating Gd targets with 0.8 and 1.06 {mu}m laser pulses of 140 fs to 10 ns duration. Maximum conversion efficiency of 0.4% was observed within a 0.6% bandwidth. A Faraday cup observed ion yield and time of flight signals for ions from plasmas generated by each laser. Ion kinetic energy was lower for shorter pulse durations, which yielded higher electron temperatures required for efficient EUV emission, due to higher laser intensity. Picosecond laser pulses were found to be the best suited to 6.7 nm EUV source generation.
Cummins, Thomas; Li Bowen; O'Gorman, Colm; Dunne, Padraig; Sokell, Emma; O'Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Otsuka, Takamitsu [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Yugami, Noboru; Higashiguchi, Takeshi [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Jiang Weihua [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan); Endo, Akira [Research Institute for Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)
High gain x-ray lasers pumped by transient collisional excitation
Science Conference Proceedings (OSTI)
We present recent results of x-ray laser amplification of spontaneous emission in Ne-like and Ni-like transient collisional excitation schemes. The plasma formation, ionization and collisional excitation can be optimized using two laser pulses of 1 ns and 1 ps duration at table-top energies of 5 J in each beam. High gain of 35 cm{sup -1} has been measured on the 147 {Angstrom} 4d{r_arrow}4p J=0{r_arrow}1 transition of Ni-like Pd and is a direct consequence of the nonstationary population inversion produced by the high intensity picosecond pulse. We report the dependence of the x-ray laser line intensity on the laser plasma conditions and compare the experimental measurements with hydrodynamic and atomic kinetics simulations for Ne-like and Ni-like lasing.
Dunn, J., LLNL
Laboratory for Laser Energetics annual report, 1 October 1991--30 September 1992
This is an annual report covering research progress on laser fusion and the OMEGA Upgrade design and development. In laser fusion, line-spectroscopy methods were demonstrated to be useful in diagnosing the core temperature and densities of polymer-shell targets; a theoretical analysis of nonlocal heat transport effects on filamentation of light in plasmas confirms that the principle mechanism driving filamentation is kinetic thermal rather than ponderomotive; a new method (spatial beam deflection) to produce laser pulses of arbitrary shape was developed; laser-plasma x-ray emission was measured using photodiode arrays; experiments on long-scale-length plasmas have shown that smoothing by spectral dispersion has proven effective in reducing Raman scattering; a method for increasing the gas-retention time of polymer shell targets was developed by overcoating them with aluminum. Experiments relating to the OMEGA Upgrade are described.
Not Available
Laser-initiated chain reactions in the partial oxidation of methane
Using laser photolysis of suitable precursor molecules to produce gas-phase free radicals, we have been studying important kinetic processes in the partial oxidation of methane. Prompt production of a relatively high concentration of free radicals via laser photolysis makes it possible to separate the thermal initiation step from the subsequent chain propagation steps. Since the conditions (temperature, pressure, and mixture composition) for rapid thermal initiation and optimum production may differ, this provides an exciting potential application for laser-induced chemistry where the laser acts as the initiation source. We report our results on the partial oxidation of methane by oxygen at moderate temperatures. A trace amount of acetone is photolyzed at 193 nm a prompt source of methyl radicals in methane-oxygen mixtures. Details of the proposed mechanism are discussed as well as application of the technique to technologies for methane conversion to transportable fuels such as methanol. 15 refs., 6 figs.
Baughcum, S.L.; Oldenborg, R.C.; Danen, W.C.; Streit, G.E.; Rofer, C.
Science Conference Proceedings (OSTI)
The development of new laser systems at the 10 Petawatt range will push laser wakefield accelerators to novel regimes, for which theoretical scalings predict the possibility to accelerate electron bunches up to tens of GeVs in meter-scale plasmas. Numerical simulations will play a crucial role in testing, probing, and optimizing the physical parameters and the setup of future experiments. Fully kinetic simulations are computationally very demanding, pushing the limits of today's supercomputers. In this paper, the recent developments in the OSIRIS framework [R. A. Fonseca et al., Lect. Notes Comput. Sci. 2331, 342 (2002)] are described, in particular the boosted frame scheme, which leads to a dramatic change in the computational resources required to model laser wakefield accelerators. Results from one-to-one modeling of the next generation of laser systems are discussed, including the confirmation of electron bunch acceleration to the energy frontier.
Martins, S. F.; Fonseca, R. A.; Vieira, J.; Silva, L. O. [GoLP/Instituto de Plasmas e Fusao Nuclear-Laboratorio Associado, Instituto Superior Tecnico, Lisbon (Portugal); Lu, W.; Mori, W. B. [University of California Los Angeles, Los Angeles, California 90095 (United States)
Chemical kinetic modelling of hydrocarbon ignition
Chemical kinetic modeling of hydrocarbon ignition is discussed with reference to a range of experimental configurations, including shock tubes, detonations, pulse combustors, static reactors, stirred reactors and internal combustion engines. Important conditions of temperature, pressure or other factors are examined to determine the main chemical reaction sequences responsible for chain branching and ignition, and kinetic factors which can alter the rate of ignition are identified. Hydrocarbon ignition usually involves complex interactions between physical and chemical factors, and it therefore is a suitable and often productive subject for computer simulations. In most of the studies to be discussed below, the focus of the attention is placed on the chemical features of the system. The other physical parts of each application are generally included in the form of initial or boundary conditions to the chemical kinetic parts of the problem, as appropriate for each type of application being addressed.
Westbrook, C.K.; Pitz, W.J.; Curran, H.J.; Gaffuri, P.; Marinov, N.M.
Philips Color Kinetics | Open Energy Information
Color Kinetics Color Kinetics Jump to: navigation, search Name Philips Color Kinetics Address 3 Burlington Woods Drive, 4th Floor Place Burlington, Massachusetts Zip 01803 Sector Efficiency Product LED lighting systems Website http://www.colorkinetics.com/ Coordinates 42.5005723°, -71.2042619° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":42.5005723,"lon":-71.2042619,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}
Science Conference Proceedings (OSTI)
High-speed mercury cadmium telluride photovoltaic detectors, sensitive to infrared emission, are investigated as a means of measuring surface temperature on a microsecond time frame during pulsed ablative discharges with Teflon trade mark sign as the ablated material. Analysis is used to derive a governing equation for detector output voltage for materials with wavelength dependent emissivity. The detector output voltage is experimentally calibrated against thermocouples embedded in heated Teflon. Experimental calibration is performed with Teflon that has been exposed to {approx}200 pulsed discharges and non-plasma-exposed Teflon and is compared to theoretical predictions to analyze emissivity differences. The diagnostic capability is evaluated with measurements of surface temperature from the Teflon propellant of electric micropulsed plasma thrusters. During the pulsed current discharge, there is insufficient information to claim that the surface temperature is accurately measured. However, immediately following the discharge, the postpulse cooling curve is measured. The statistical spread of postpulse surface temperature from shot to shot, most likely due to arc constriction and localization, is investigated to determine an operational envelope for postpulse temperature and mass ablation. This information is useful for determining postpulse ablation contributions to mass loss as well as evaluation of theoretical discharge models currently under development.
Antonsen, Erik L.; Burton, Rodney L.; Reed, Garrett A.; Spanjers, Gregory G. [University of Illinois at Urbana-Champaign, Illinois 61801 (United States); ERC Inc., Edwards AFB, California 93524 (United States); Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)
Melting of nanocrystals embedded in a crystal matrix heated by nanosecond laser pulses
The kinetics of phase transformations of nanocrystals in a crystal matrix is considered upon non-stationary heating by laser pulses. The melting and crystallization kinetics of nanocrystals is described taking into account their size, shape, elemental composition, and elastic deformations appearing due to the mismatch of the lattice constants for nanocrystals and the matrix. The possibility of decreasing the dispersion of nanocrystals over their size in heterostructures with quantum dots is predicted. As an example, melting of Ge nanocrystals in a Si matrix is considered.
Zinoviev, V. A., E-mail: email@example.com; Dvurechenskii, A. V.; Smagina, Zh. V., E-mail: firstname.lastname@example.com [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Ivlev, G. D.; Gatskevich, E. I.; Malevich, V. L. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)
This paper reviews the status of direct-drive inertial confinement fusion (ICF) research at the University of Rochester's Laboratory for Laser Energetics (LLE). LLE's goal is to demonstrate direct-drive ignition on the National Ignition Facility (NIF) by 2014. Baseline "all-DT" NIF direct-drive ignition target designs have been developed that have a predicted gain of 45 (1-D) at a NIF drive energy of ~1.6 MJ. Significantly higher gains are calculated for targets that include a DT-wicked foam ablator. This paper also reviews the results of both warm fuel and initial cryogenic-fuel spherical target implosion experiments carried out on the OMEGA UV laser. The results of these experiments and design calculations increase confidence that the NIF direct-drive ICF ignition goal will be achieved.
McCrory, R.L.; Meyerhofer, D.D.; Loucks, S.J.; Skupsky, S.; Bahr, R.E.; Betti, R.; Boehly, T.R.; Craxton, R.S.; Collins, T.J.B.; Delettrez, J.A.; Donaldson, W.R.; Epstein, R.; Fletcher, K.A.; Freeman, C.; Frenje, J.A.; Glebov, V.Yu.; Goncharov, V.N.; Harding, D.R.; Jaanimagi, P.A.; Keck, R.L.; Kelly, J.H.; Kessler, T.J.; Kilkenny, J.D.; Knauer, J.P.; Li, C.K.; Lund, L.D.; Marozas, J.A.; McKenty, P.W.; Marshall, F.J.; Morse, S.F.B.; Padalino, S.; Petrasso, R.D.; Radha, P.B.; Regan, S.P.; Roberts, S.; Sangster, T.C.; Seguin, F.H.; Seka, W.; Smalyuk, V.A.; Soures, J.M.; Stoeckl, C.; Thorp, K.A.; Yaakobi, B.; Zuegel, J.D.
Model Independent Bounds on Kinetic Mixing
New Abelian vector bosons can kinetically mix with the hypercharge gauge boson of the Standard Model. This letter computes the model independent limits on vector bosons with masses from 1 GeV to 1 TeV. The limits arise from the numerous e{sup +}e{sup -} experiments that have been performed in this energy range and bound the kinetic mixing by {epsilon} {approx}< 0.03 for most of the mass range studied, regardless of any additional interactions that the new vector boson may have.
Hook, Anson; Izaguirre, Eder; Wacker, Jay G.; /SLAC
Fast Magnetic Reconnection in Laser-Produced Plasma Bubbles
Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pileup at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with two-fluid effects, we find that the ultimate reconnection time is insensitive to the nominal system Alfven time.
Fox, W.; Bhattacharjee, A.; Germaschewski, K. [Center for Integrated Computation and Analysis of Reconnection and Turbulence, and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of New Hampshire, Durham, New Hampshire 03824 (United States)
CIGS P1, P2, P3 Scribing Processes using a Pulse Programmable Industrial Fiber Laser: Preprint
We describe a novel set of laser processes for the CIGS P1, P2 and P3 scribing steps, the development of which has been enabled by a unique pulse-programmable fiber laser. We find that the unique pulse control properties of this 1064 nm wavelength laser have significant effects on the material removal dynamics of the various film layers in the CIGS material system. In the case of the P2 and P3 processes, the shaped pulses create new laser/material interaction effects that permit the material to be cleanly and precisely removed with zero Heat Affected Zone (HAZ) at the edges of the scribe. The new P2 and P3 processes we describe demonstrate the first use of infrared nanosecond laser pulses that eliminate the HAZ and the consequent localized compositional changes in the CIGS absorber material that result in poor shunt resistance. SEM micrographs and EDX compositional scans are presented. For the P1 scribe, we process the bi-layer molybdenum from the film side as well as through the glass substrate. Microscopic inspection and compositional analysis of the scribe lines are not sufficient to determine electrical and optical performance in working PV modules. Therefore, to demonstrate the applicability of the infrared pulse-programmable laser to all three scribing processes for thin-film CIGS, we fabricate small-size multiple-cell monolithically interconnected mini-modules in partnership with the National Renewable Energy Laboratory (Golden, Colorado). A total of four mini-modules are produced, two utilizing all laser scribing, and two with the P2 and P3 steps mechanically scribed (by a third party) for reference. Mini-module performance data measured at NREL is presented, and we also discuss the commercialization potential of the new single-laser CIGS scribing process. Finally we present a phenomenological model to describe this physics underlying this novel ablation process.
Rekow, M.; Murison, R.; Panarello, T.; Dunsky, C.; Dinkel, C.; Nikumb, S.; Pern, F. J.; Mansfield, L.
A blue-green laser (450--550 nm) uses a host crystal doped with Tm[sup 3+]. The Tm[sup 3+] is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconductor laser, e.g., GaAlAs and InGaAlP. 3 figs.
Nguyen, D.C.; Faulkner, G.E.
A blue-green laser (450-550 nm) uses a host crystal doped with Tm{sup 3+}. The Tm{sup 3+} is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconducting laser, e.g., GaAlAs and InGaAlP.
Nguyen, Dinh C.; Faulkner, G.E.
A blue-green laser (450-550 nm) uses a host crystal doped with Tm.sup.3+. The Tm.sup.+ is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconductor laser, e.g., GaAlAs and InGaAlP.
Nguyen, Dinh C. (Los Alamos, NM); Faulkner, George E. (Los Alamos, NM)
Laser fusion pulse shape controller
An apparatus for controlling the pulse shape, i.e., the pulse duration and intensity pattern, of a pulsed laser system, and which is particularly well adapted for controlling the pellet ignition pulse in a laser-driven fusion reaction system. The apparatus comprises a laser generator for providing an optical control pulse of the shape desired, a pulsed laser triggered by the control pulse, and a plurality of optical Kerr-effect gates serially disposed at the output of the pulsed laser and selectively triggered by the control pulse to pass only a portion of the pulsed laser output generally corresponding in shape to the control pulse.
Siebert, Larry D. (Ann Arbor, MI)
Investigation of the kinetics of surface-limited thin film growth of SiGe alloys
The kinetics of surface-limited thin film growth of SiGe alloys was investigated by time-resolved surface differential reflectometry. The source gas, mixtures of disilane and digermane in ratios from 1:1 to 6:1 in helium carrier gas, was delivered to a heated substrate by a fast-acting pulsed molecular jet valve. The adsorption and desorption kinetics were determined from the surface differential reflectance signal obtained using a polarized, high-stability HeNe probe laser. Thin film growth was studied in the temperature range of 400--600{degrees}C on Si(001) substrates. Preferential incorporation of digermane into the film produces an alloy composition that depends upon but does not mirror the gas composition. For all gas mixtures, there is a strong temperature dependence of the rate at which the adsorption layer decomposes into film plus by-product. The kinetic data and the alloy compositions provide a basis for deducing some of the characteristics of the reaction sequence that leads to SiGe alloy thin film growth.
Sharp, J.W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy; Eres, G. [Oak Ridge National Lab., TN (United States)
Investigation of the kinetics of surface-limited thin film growth of SiGe alloys
The kinetics of surface-limited thin film growth of SiGe alloys was investigated by time-resolved surface differential reflectometry. The source gas, mixtures of disilane and digermane in ratios from 1:1 to 6:1 in helium carrier gas, was delivered to a heated substrate by a fast-acting pulsed molecular jet valve. The adsorption and desorption kinetics were determined from the surface differential reflectance signal obtained using a polarized, high-stability HeNe probe laser. Thin film growth was studied in the temperature range of 400--600[degrees]C on Si(001) substrates. Preferential incorporation of digermane into the film produces an alloy composition that depends upon but does not mirror the gas composition. For all gas mixtures, there is a strong temperature dependence of the rate at which the adsorption layer decomposes into film plus by-product. The kinetic data and the alloy compositions provide a basis for deducing some of the characteristics of the reaction sequence that leads to SiGe alloy thin film growth.
Sharp, J.W. (Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy); Eres, G. (Oak Ridge National Lab., TN (United States))
Variable emissivity laser thermal control system
A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.
Milner, Joseph R. (Livermore, CA)
Other Projects [Laser Applications Laboratory] - Nuclear Engineering
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Other Projects Other Projects Capabilities Engineering Experimentation Reactor Safety Experimentation Aerosol Experiments System Components Laser Applications Overview Laser Oil & Gas Well Drilling Laser Heat Treatment Laser Welding of Metals On-line Monitoring Laser Beam Delivery Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Laser Applications Laboratory Other projects Bookmark and Share HIGH POWER LASER BEAM DELIVERY High-power laser-beam delivery with conventional and fiber optics DECONTAMINATION & DECOMMISSIONING Laser processing technology for decontamination of surfaces
Science Conference Proceedings (OSTI)
The kinetics of the reactions of C{sub 2}H{sub 5} radical with Co(NH{sub 3}){sub 5}X{sup 2+}, Ru(NH{sub 3}){sub 5}X{sup 2+}, and Co(dmgH){sub 2} (X) (Y) (X = Br, Cl, N{sub 3}, SCN; Y = H{sub 2}O, CH{sub 3}CN) complexes were studied using laser flash photolysis of ethylcobalt complexes. The kinetics were obtained by the kinetic probe method. Some relative rate constants were also determined by a competition method based on ethyl halide product ratios. The kinetics of colligation reactions of a series of alkyl radicals with {beta}-Ni(cyclam){sup 2+} were studied using flaser flash photolysis of alkylcobalt complexes. Again, the kinetics were obtained by employing the kinetic probe competition method. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H{sub 2}O{sup 2+} were studied. Activation parameters were obtained for the unimolecular homolysis of C{sub 2}H{sub 5}Ni(cyclam)H{sub 2}O{sup 2+}. Kinetic and thermodynamic data obtained from these reactions were compared with those for the {sigma}-bonded organometallic complexes. The kinetics of the unimolecular homolysis of a series of RNi(cyclam)H{sub 2}O{sup 2+} complexes were studied by monitoring the formation of the oxygen insertion product RO{sub 2}Ni(cyclam)H{sub 2}O{sup 2+}. The higher rate constants for the reactions of alkyl radicals with oxygen in solution, as compared with those measured in the gas phase, were discussed. 30 refs.
Kelley, D.
Novel Percutaneous Radiofrequency Ablation of Portal Vein Tumor Thrombus: Safety and Feasibility
We report our experience of the safety of partial recanalization of the portal vein using a novel endovascular radiofrequency (RF) catheter for portal vein tumor thrombosis. Six patients with liver cancer and tumor thrombus in the portal vein underwent percutaneous intravascular radiofrequency ablation (RFA) using an endovascular bipolar RF device. A 0.035-inch guidewire was introduced into a tributary of the portal vein and through which a 5G guide catheter was introduced into the main portal vein. After manipulation of the guide catheter over the thrombus under digital subtraction angiography, the endovascular RF device was inserted and activated around the thrombus. There were no observed technique specific complications, such as hemorrhage, vessel perforation, or infection. Post-RFA portography showed partial recanalization of portal vein. RFA of portal vein tumor thrombus in patients with hepatocellular carcinoma is technically feasible and warrants further investigation to assess efficacy compared with current recanalization techniques.
Mizandari, Malkhaz [High Technology Medical Center, Tbilisi State Medical University (Georgia)] [High Technology Medical Center, Tbilisi State Medical University (Georgia); Ao, Guokun [The 309 Hospital of People's Liberation Army, Department on Oncology (China)] [The 309 Hospital of People's Liberation Army, Department on Oncology (China); Zhang Yaojun; Feng Xi [Imperial College London, Department of Surgery and Cancer (United Kingdom)] [Imperial College London, Department of Surgery and Cancer (United Kingdom); Shen Qiang [The First Minimally Invasive Department of Eastern Hepatobiliary Surgery Hospital (China)] [The First Minimally Invasive Department of Eastern Hepatobiliary Surgery Hospital (China); Chen Minshan [Cancer Centre of Sun Yat-Sen University, Department of Hepatobiliary Surgery (China)] [Cancer Centre of Sun Yat-Sen University, Department of Hepatobiliary Surgery (China); Lau, Wan Yee [Chinese University of Hong Kong, Department of Surgery, Faculty of Medicine (Hong Kong)] [Chinese University of Hong Kong, Department of Surgery, Faculty of Medicine (Hong Kong); Nicholls, Joanna; Jiao Long; Habib, Nagy, E-mail: firstname.lastname@example.com [Imperial College London, Department of Surgery and Cancer (United Kingdom)] [Imperial College London, Department of Surgery and Cancer (United Kingdom)
Science Conference Proceedings (OSTI)
A rare life-threatening complication during percutaneous cryoablation of an adrenal gland metastasis from a lung carcinoma is reported. The patient presented hypertensive crisis at the beginning of the thawing cycle, followed by electrocardiographic change which necessitated interruption of the procedure and his transfer to the intensive care unit with suspicion of heart infarct. There was a slight increase in cardiac enzyme levels, and ventricular angiography demonstrated transient hypokinesis-dyskinesis of the mid left ventricular segments without apical involvement, while the coronary arteries showed no significant stenosis on coronarography. These findings led to the diagnosis of Takotsubo cardiomyopathy left ventricular dysfunction syndrome. This is the first case of Takotsubo cardiomyopathy occurring as a complication during percutaneous ablation of an adrenal gland tumor.
Tsoumakidou, Georgia, E-mail: firstname.lastname@example.com; Buy, Xavier, E-mail: firstname.lastname@example.com [University Hospital of Strasbourg, Department of Non Vascular Interventional Radiology (France); Zickler, Pierre, E-mail: email@example.com [University Hospital of Strasbourg, Department of Anaesthesiology (France); Zupan, Michel, E-mail: firstname.lastname@example.com; Douchet, Marie-Pierre, E-mail: email@example.com [University Hospital of Strasbourg, Department of Cardiology (France); Gangi, Afshin, E-mail: email@example.com [University Hospital of Strasbourg, Department of Non Vascular Interventional Radiology (France)
Dynamic stabilization of Rayleigh-Taylor instability in an ablation front
Science Conference Proceedings (OSTI)
Dynamic stabilization of Rayleigh-Taylor instability in an ablation front is studied by considering a modulation in the acceleration that consists of sequences of Dirac deltas. This allows obtaining explicit analytical expressions for the instability growth rate as well as for the boundaries of the stability region. As a general rule, it is found that it is possible to stabilize all wave numbers above a certain minimum value k{sub m}, but the requirements in the modulation amplitude and frequency become more exigent with smaller k{sub m}. The essential role of compressibility is phenomenologically addressed in order to find the constraint it imposes on the stability region. The results for some different wave forms of the acceleration modulation are also presented.
Piriz, A. R.; Di Lucchio, L.; Rodriguez Prieto, G. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain) and Instituto de Investigaciones Energeticas, 13071 Ciudad Real (Spain)
Dynamic Stabilization of the Ablative Rayleigh-Taylor Instability for Heavy Ion Fusion
Dynamic stabilization of the ablative Rayleigh-Taylor instability of a heavy ion fusion target induced by a beam wobbling system is studied. Using a sharp-boundary model and Courant-Synder theory, it is shown, with an appropriately chosen modulation waveform, that the instability can be sta- bilized in certain parameter regimes. It is found that the stabilization e ect has a strong dependence on the modulation frequency and the waveform. Modulation with frequency comparable to the instability growth rate is the most e ective in terms of stabilizing the instability. A modulation with two frequency components can result in a reduction of the growth rate larger than the sum of that due to the two components when applied separately.
Hong Qin, Ronald C. Davidson and B. Grant Logan
Science Conference Proceedings (OSTI)
Telluride (CdTe) is a front-runner photovoltaic (PV) material because it has already attained efficiencies above 16%. The fabrication of CdTe nanoparticles has aroused considerable interest because of their potential application as active layer in organic/inorganic hybrid solar cells. They can also be used for sensitisation of wide band gap semiconductors. In this work, we explore pulsed electron beam deposition (PED) technique to fabricate CdTe nanoparticles. Two ablation parameters, namely background gas pressure and electron energy were varied to investigate their effects on the nanoparticle formation. AFM and optical transmission measurements indicate that we have fabricated CdTe nanocrystalline films exhibiting quantum confinement effect. These films contain scattered nanoparticles with diameters varying from 40 nm to 500 nm, which contribute to the optical absorption near the bulk bandgap energy. However, increasing the background pressure to 19 mTorr improves the nanocrystalline film uniformity.
Jackson, E.; Aga, R. Jr.; Steigerwald, A.; Ueda, A.; Pan, Z.; Collins, W. E.; Mu, R. [Department of Physics, Fisk University, 1000 17th Ave N, Nashville TN 37208 (United States)
The ablative, fast pyrolysis system was relocated to SERI's new, permanent Field Test Laboratory. Pyrolysis system modifications were made to increase the energy available to the vortex reactor and to enhance the collection efficiency of primary pyrolysis vapors. Mathematical modeling of the vapor cracker has resulted in the ability to accurately predict experimental results with respect to the thermal cracking of the primary vapors, the generation of noncondensible gases, and the gas composition. The computer algorithm of this model can be readily used to perform experimental simulation and/or reactor scale-up due to its fundamental nature. Preliminary screening tests with pure ZSM-5 zeolite catalyst, supplied by Mobil Research and Development Corporation, have shown promise for the conversion of primary pyrolysis oil vapors to aromatic hydrocarbons; i.e., gasoline.
Diebold, J. P.; Scahill, J. W.; Evans, R. J.
Laser Materials Processing: Past, Present and Future
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, Materials Science & Technology 2010. Symposium, Laser Applications in Materials Processing. Presentation Title, Laser Materials�...
The nitrogen ion laser pumped by charge transfer
Science Conference Proceedings (OSTI)
Charge transfer from He/sup +//sub 2/ to N/sub 2/ has been used in a variety of devices to pump significant levels of inversion of the B/sup 2/..sigma../SUB u/ electronic transistion of N/sup +//sub 2/. Laser output has been achieved at three wavelengths, 391.4, 427.8, and 470.9 nm. Each has corresponded to a transition from the same upper laser level to lower levels having vibrational quantum numbers equal to 0, 1, and 2, respectively. With proper mirror sets each has been individually excited. Studies of the scaling and efficiency at which the laser output could be obtained have been made with devices pumped by e-beams, preionized avalanche discharges, and preionized resonant and traveling wave discharges. The possible efficiencies for the extraction of the energies stored in the inversions have been examined for various configurations of the coupling of the optical fields to the plasmas. Resulting devices have included self-excited oscillators, regenerative amplifiers, and master oscillator power amplifiers. The experimental results have supported a kinetic model which generally explains the unique features of the nitrogen ion laser. Of particular interest is the capacity of these systems to support the simultaneous optimization of both scale and efficiency. With e-beam excitation optical power densities of 320 MW X 1/sup -1/ have been achieved at a constant power transfer efficiency of 3 percent. With resonant discharge excitation 44 MW X 1/sup -1/ have been demonstrated at power conversion efficiencies of 2 percent and overall efficiencies ranging from 0.2 to 0.4 percent. From these results the kinetic model has projected an overall efficiency of 0.9 percent to be ultimately realized in a discharge device.
Collins, C.B.
Comparison of Substrate Processing Via Laser and Laser-Sustained ...
Science Conference Proceedings (OSTI)
About this Abstract. Meeting, Materials Science & Technology 2010. Symposium, Laser Applications in Materials Processing. Presentation Title, Comparison of�...
We can now produce intense, coherent light at wavelengths where no conventional lasers exist. The recent successes of devices known as free-electron lasers mark a striking confluence of two conceptual developments that themselves are only a few decades old. The first of these, the laser, is a product of the fifties and sixties whose essential characteristics have made it a staple resource in almost every field of science and technology. In a practical sense, what defines a laser is its emission of monochromatic, coherent light (that is, light of a single wavelength, with its waves locked in step) at a wavelength in the infrared, visible, or ultraviolet region of the electromagnetic spectrum. A second kind of light, called synchrotron radiation, is a by-product of the age of particle accelerators and was first observed in the laboratory in 1947. As the energies of accelerators grew in the 1960s and 70s, intense, incoherent beams of ultraviolet radiation and x--rays became available at machines built for high-energy physics research. Today, several facilities operate solely as sources of synchrotron light. Unlike the well-collimated monochromatic light emitted by lasers, however, this incoherent radiation is like a sweeping searchlight--more accurately, like the headlight of a train on a circular track--whose wavelengths encompass a wide spectral band. Now, in several laboratories around the world, researchers have exploited the physics of these two light sources and have combined the virtues of both in a single contrivance, the free-electron laser, or FEL (1). The emitted light is laserlike in its narrow, sharply peaked spectral distribution and in its phase coherence, yet it can be of a wavelength unavailable with ordinary lasers. Furthermore, like synchrotron radiation, but unlike the output of most conventional lasers, the radiation emitted by free-electron lasers can be tuned, that is, its wavelength can be easily varied across a wide range. The promise of this new technology extends from the fields of solid-state physics, gas- and liquid-phase photochemistry, and surface catalysis to futuristic schemes for ultrahigh-energy linear accelerators.
Sessler, A.M.; Vaughan, D.
Study of photoinduced absorption by the method of modified laser photothermal radiometry
The application of the method of modified laser photothermal radiometry for studying the photoinduced absorption in thin films is considered. The sensitivity of the method is estimated. The mechanism of induced near-IR absorption in titanium dioxide films is proposed and the nature of surface defects responsible for this process is explained. It is shown that kinetic equations describing monomolecular recombination are consistent with the experimental dependences for the thermal activation energy of defects equal to 0.17{+-}0.04 eV. (laser applications and other topics in quantum electronics)
Skvortsov, L A; Maksimov, E M; Tuchkov, A A [Academy of Cryptography, Communication and Informatics, Moscow (Russian Federation)
Ocean Circulation Kinetic Energy: Reservoirs, Sources,
. The coupling of the generation of different energy forms in the dynamics (in either balanced or wave motions are almost nonexistent in the ocean. www.annualreviews.org · Ocean Circulation Kinetic Energy 255 Annu.Rev.Fluid processes? Are the seemingly different dynamical ranges coupled? 2. THE OCEANIC ENERGY BUDGET We begin
Ferrari, Raffaele
Thermodynamics and Kinetics of a Brownian Motor
Thermodynamics and Kinetics of a Brownian Motor R. Dean Astumian Nonequilibrium fluctuations particle separation and the design of molecular motors and pumps. A small particle in a liquid is subject in conjunction with an- isotropy to drive a motor in the context of a "ratchet and pawl" device shrunk to micro
Linke, Heiner
KINETICS, STABILITY, AND CONTROL. A Selected Bibliography
References to 529 articles on nuclear reactor control, kinetics, and stability published before autumn 1962 are included. Emphasis is on calculations and theory since the references serve as an aid in analyzing the dynamic behavior of SNAP reactor systems. (D.C.W.)
Johnson, R.L.
Reaction kinetics for remodeling oil shale retorting
Results from recent laboratory kinetic studies at the Lawrence Livermore Laboratory (LLL) on gasification, pyrolysis, and mineral reactions in oil shale are presented. The specific pyrolysis reactions investigated include the decomposition of kerogen, the evolution of oil, hydrogen and C/sub 2/ plus C/sub 3/ hydrocarbons and the formation of a carbonaceous residue. Data describing the evolution of H/sub 2/ and CH/sub 4/ during secondary pyrolysis of the carbonaceous residue are also presented. The mineral reaction kinetics discussed include the decomposition and/or reaction (with silica or silicates) of calcite, dolomite, dawsonite and nahcolite. Rate equations describing the effects of CO/sub 2/ and steam on the reactions of calcite and dolomite are presented. Finally, kinetics describing gasification of the carbonaceous residue by CO/sub 2/ and H/sub 2/O are examined. The above kinetic data are summarized in a set of rate expressions that can be used in numerical modeling of oil shale retorting. The rate equations are general enough for modeling both in-situ and surface retorting processes.
Campbell, J.H.; Burnham, A.K.
Radiation from Kinetic Poynting Flux Acceleration
We derive analytic formulas for the power output and critical frequency of radiation by electrons accelerated by relativistic kinetic Poynting flux, and validate these results with Particle-In-Cell plasma simulations. We find that the in-situ radiation power output and critical frequency are much below those predicted by the classical synchrotron formulae. We discuss potential astrophysical applications of these results.
Edison Liang; Koichi Noguchi
Insulative laser shell coupler
A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.
Arnold, Phillip A. (Livermore, CA); Anderson, Andrew T. (Livermore, CA); Alger, Terry W. (Tracy, CA)
It is well-known how to control the spatial output from a laser, with most solutions to date involving customised intra-cavity elements in the form of apertures, diffractive optics and free-form mirrors. These optical elements require considerable design and fabrication effort and suffer from the further disadvantage of being immutably connected to the selection of a particular spatial mode. Consequently, most laser systems are designed for the ubiquitous Gaussian mode, whereas it is clear that there are many instances when a customised mode would be preferable. We overcome these limitations with the first digital laser, comprising an electrically addressed reflective phase-only spatial light modulator as an intra-cavity holographic mirror. The phase and amplitude of the holographic mirror may be controlled as simply as writing a new gray-scale image (computer generated hologram) to the device: on-demand laser modes. We show that we can digitally control the laser modes with ease, albeit with higher round-tri...
Ngcobo, Sandile; Burger, Liesl; Forbes, Andrew
Femtosecond laser interactions with semiconductor and dielectric materials
Electronic excitation-relaxation processes induced by ultra-short laser pulses are studied numerically for semiconductors and dielectric materials (Si, quartz). A detailed kinetic approach is used in the calculations accounting for electron-photon-phonon, electron-phonon and electron-electron scatterings. In addition, both laser field ionization ranging from multi-photon to tunneling one, and electron impact (avalanche) ionization processes are included in the model. Based on the performed calculations we study the relaxation time as a function of laser parameters. It is shown that this time depends on the density of the created free carriers, which in turn is a nonlinear function of laser intensity. In addition, a simple damage criterion is proposed based on the mean electron energy density rather than on critical free electron density. This criterion gives a reasonable agreement with the available experimental data practically without adjustable parameters. Furthermore, the performed modeling provides energy absorbed in the target, conditions for damage of dielectric materials, as well as conditions for surface plasmon excitation and for periodic surface structure formation on the surface of semiconductor materials.
Shcheblanov, Nikita S.; Derrien, Thibault J. Y.; Itina, Tatiana E. [Laboratoire Hubert Curien, CNRS//Universite Jeann Monnet, 18 rue du Prof. Benoit Lauras, 42000 Saint-Etienne (France); Laboratoire Lasers, Plasmas et Procedes Photoniques, CNRS//Universite de la Mediterranee, 162 avenue de Luminy, 13288, Marseille (France); Laboratoire Hubert Curien, CNRS//Universite Jeann Monnet, 18 rue du Prof. Benoit Lauras, 42000 Saint-Etienne (France)
Fiber Laser Front Ends for High Energy, Short Pulse Lasers
We are developing a fiber laser system for short pulse (1-10ps), high energy ({approx}1kJ) glass laser systems. Fiber lasers are ideal for these systems as they are highly reliable and enable long term stable operation.
Dawson, J; Messerly, M; Phan, H; Siders, C; Beach, R; Barty, C
Robotic laser welding: seam sensor and laser focal frame registration
Science Conference Proceedings (OSTI)
Robotic laser welding places extreme demands on the spatial accuracy with which the robot must position the focal point of the laser with respect to the joint to be welded. The required level of accuracy is difficult to achieve in a production environment ... Keywords: Calibration, Laser welding, Robots, Seam tracking
J. P. Huissoon
Chapter 31. Microfluidic Fiber Lasers Microfluidic Fiber Lasers
at the water/oil interface. We have shown that in maintaining the same pump beam energy, the fiber laser can based pressure sensors. Custom made hermetic optical coupler oil Pump Light Radially Emitted Laser Light hermetic optical coupler oil Pump Light Radially Emitted Laser Light from R6G-doped water plug Microfluidic
Self-tuning method for monitoring the density of a gas vapor component using a tunable laser
The present invention relates to a vapor density monitor and laser atomic absorption spectroscopy method for highly accurate, continuous monitoring of vapor densities, composition, flow velocity, internal and kinetic temperatures and constituent distributions. The vapor density monitor employs a diode laser, preferably of an external cavity design. By using a diode laser, the vapor density monitor is significantly less expensive and more reliable than prior art vapor density monitoring devices. In addition, the compact size of diode lasers enables the vapor density monitor to be portable. According to the method of the present invention, the density of a component of a gas vapor is calculated by tuning the diode laser to a frequency at which the amount of light absorbed by the component is at a minimum or a maximum within about 50 MHz of that frequency. Laser light from the diode laser is then transmitted at the determined frequency across a predetermined pathlength of the gas vapor. By comparing the amount of light transmitted by the diode laser to the amount of light transmitted after the laser light passes through the gas vapor, the density of the component can be determined using Beer`s law. 6 figs.
Hagans, K.; Berzins, L.; Galkowski, J.; Seng, R.
Chemical Kinetic Modeling of Hydrogen Combustion Limits
Science Conference Proceedings (OSTI)
A detailed chemical kinetic model is used to explore the flammability and detonability of hydrogen mixtures. In the case of flammability, a detailed chemical kinetic mechanism for hydrogen is coupled to the CHEMKIN Premix code to compute premixed, laminar flame speeds. The detailed chemical kinetic model reproduces flame speeds in the literature over a range of equivalence ratios, pressures and reactant temperatures. A series of calculation were performed to assess the key parameters determining the flammability of hydrogen mixtures. Increased reactant temperature was found to greatly increase the flame speed and the flammability of the mixture. The effect of added diluents was assessed. Addition of water and carbon dioxide were found to reduce the flame speed and thus the flammability of a hydrogen mixture approximately equally well and much more than the addition of nitrogen. The detailed chemical kinetic model was used to explore the detonability of hydrogen mixtures. A Zeldovich-von Neumann-Doring (ZND) detonation model coupled with detailed chemical kinetics was used to model the detonation. The effectiveness on different diluents was assessed in reducing the detonability of a hydrogen mixture. Carbon dioxide was found to be most effective in reducing the detonability followed by water and nitrogen. The chemical action of chemical inhibitors on reducing the flammability of hydrogen mixtures is discussed. Bromine and organophosphorus inhibitors act through catalytic cycles that recombine H and OH radicals in the flame. The reduction in H and OH radicals reduces chain branching in the flame through the H + O{sub 2} = OH + O chain branching reaction. The reduction in chain branching and radical production reduces the flame speed and thus the flammability of the hydrogen mixture.
Pitz, W J; Westbrook, C K
Science Conference Proceedings (OSTI)
... used traditional cooling beams at 852 nm in the x-y plane, but replaced the usual two beams along z with lasers at 795 nm. This laser only couples ...
Laser welding of electrical interconnections
Processes and equipment have been developed for welding thin aluminum and copper foils using a Nd : YAG laser. Laser welding provides an alternate technique with improved quality for welding these types of electrical terminations.
Bauer, F.R.
Isothermal Ice Crystallization Kinetics in the Gas-Diffusion...
NLE Websites -- All DOE Office Websites (Extended Search)
Isothermal Ice Crystallization Kinetics in the Gas-Diffusion Layer of a Proton-Exchange-Membrane Fuel Cell Title Isothermal Ice Crystallization Kinetics in the Gas-Diffusion Layer...
The Vertical Partition of Oceanic Horizontal Kinetic Energy
Science Conference Proceedings (OSTI)
To produce an interpretation of the surface kinetic energy as measured by altimeters, a survey is made of the vertical structure of kinetic energy profiles in a large number of globally distributed long current meter records. Although the data ...
Carl Wunsch
Evaluating Mesoscale NWP Models Using Kinetic Energy Spectra
Science Conference Proceedings (OSTI)
Kinetic energy spectra derived from observations in the free atmosphere possess a wavenumber dependence of k?3 for large scales, characteristic of 2D turbulence, and transition to a k?5/3 dependence in the mesoscale. Kinetic energy spectra ...
William C. Skamarock
Zettawatt-Exawatt Lasers and Their Applications in Ultrastrong-Field Physics High Energy Front
Since its birth, the laser has been extraordinarily effective in the study and applications of laser-matter interaction at the atomic and molecular level and in the nonlinear optics of the bound electron. In its early life, the laser was associated with the physics of electron volts and of the chemical bond. Over the past fifteen years, however, we have seen a surge in our ability to produce high intensities, five to six orders of magnitude higher than was possible before. At these intensities, particles, electrons and protons, acquire kinetic energy in the mega-electron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level $10^{26-28} $W/cm$^2$ in the coming decade, much beyond the current and near future intensity regime $10^{23} $W/cm$^2$, taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity co...
Tajima, T
Laser Assisted Emittance Exchange
Science Conference Proceedings (OSTI)
We describe here the laser assisted emittance exchange (LAEE) technique. A laser operating in the transverse mode (TEM10 or TEM01) is used to interact with the electron beam in a dispersive region and to initiate the transverse-to-longitudinal emittance exchange. It is shown that with the LAEE one can generate an electron beam with ultralow transverse emittance, which allows one to significantly bring down the size of an X-ray free electron laser (FEL) and greatly extend the availability of these light sources. The technique can also be used to enhance the performances of X-ray FELs in storage rings. The timing and energy jitter problems for the standard emittance exchange and LAEE techniques are also discussed.
Xiang, Dao; /SLAC
The development of microsatellites requires the development of engines to modify their orbit. It is natural to use solar energy to drive such engines. For an unlimited energy source the optimal thruster must use a minimal amount of expendable material to minimize launch costs. This requires the ejected material to have the maximal velocity and, hence, the ejected atoms must be as light as possible and be ejected by as high an energy density source as possible. Such a propulsion can be induced by pulses from an ultra-short laser. The ultra-short laser provides the high-energy concentration and high-ejected velocity. We suggest a microthruster system comprised of an inflatable solar concentrator, a solar panel, and a diode-pumped fiber laser. We will describe the system design and give weight estimates.
Rubenchik, A M; Beach, R; Dawson, J; Siders, C W
A plurality of pivotal reflectors direct a high-power laser beam onto a workpiece, and a rotatable reflector is movable to a position wherein it intercepts the beam and deflects a major portion thereof away from its normal path, the remainder of the beam passing to the pivotal reflectors through an aperture in the rotating reflector. A plurality of targets are movable to positions intercepting the path of light traveling to the pivotal reflectors, and a preliminary adjustment of the latter is made by use of a low-power laser beam reflected from the rotating reflector, after which the same targets are used to make a final adjustment of the pivotal reflectors with the portion of the high-power laser beam passed through the rotating reflector.
Kasner, William H. (11686 Althea Dr., Pittsburgh, PA 15235); Racki, Daniel J. (712 Union Cemetery Rd., Greensburg, PA 15601); Swenson, Clark E. (228 Scott Dr., Monroeville, PA 15146)
Stimulated radiative laser cooling
Building a refrigerator based on the conversion of heat into optical energy is an ongoing engineering challenge. Under well-defined conditions, spontaneous anti-Stokes fluorescence of a dopant material in a host matrix is capable of lowering the host temperature. The fluorescence is conveying away a part of the thermal energy stored in the vibrational oscillations of the host lattice. In particular, applying this principle to the cooling of (solid-state) lasers opens up many potential device applications, especially in the domain of high-power lasers. In this paper, an alternative optical cooling scheme is outlined, leading to radiative cooling of solid-state lasers. It is based on converting the thermal energy stored in the host, into optical energy by means of a stimulated nonlinear process, rather than a spontaneous process. This should lead to better cooling efficiencies and a higher potential of applying the principle for device applications.
Muys, Peter
A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.
Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.
Piezoelectric measurement of laser power
A method for measuring the energy of individual laser pulses or a series of laser pulses by reading the output of a piezoelectric (PZ) transducer which has received a known fraction of the total laser pulse beam. An apparatus is disclosed that reduces the incident energy on the PZ transducer by means of a beam splitter placed in the beam of the laser pulses. 4 figs.
Deason, V.A.; Johnson, J.A.; Telschow, K.L.
Laser Application for Material Processing
Science Conference Proceedings (OSTI)
Oct 10, 2012 ... Advanced Materials, Processes and Applications for Additive Manufacturing: Laser Application for Material Processing Program Organizers:�...
CRC handbook of laser science and technology. Volume 1. Lasers and masers
Science Conference Proceedings (OSTI)
This book describes various types of lasers and masers. The following topics are discussed in detail: types and comparisons of laser sources, crystal and glass lasers, semiconductor lasers, organic dye and other liquid lasers, free-electron and x-ray lasers, masers and laser safety.
Weber, M.J.
Nonlinear kinetic modeling of stimulated Raman scattering in a multidimensional geometry
Science Conference Proceedings (OSTI)
In this paper, we derive coupled envelope equations modeling the growth of stimulated Raman scattering (SRS) in a multi-dimensional geometry and accounting for nonlinear kinetic effects. In particular, our envelope equations allow for the nonlinear reduction of the Landau damping rate, whose decrease with the plasma wave amplitude depends on the rate of side-loss. Account is also made of the variations in the extent of the plasma wave packet entailed by the collisionless dissipation due to trapping. The dephasing between the electron plasma wave (EPW) and the laser drive, as well as the self-focussing of the plasma wave, both induced by the EPW nonlinear frequency shift, are also included in our envelope equations. These equations are solved in a multi-dimensional geometry using our code dubbed BRAMA, whose predictions regarding the evolution of Raman reflectivity as a function of the laser intensity are compared against previously published particle in cell results, thus illustrating the ability of BRAMA simulations to provide the correct laser threshold intensity for SRS as well as the right order of magnitude of Raman reflectivity above threshold.
Benisti, D.; Morice, O.; Gremillet, L.; Friou, A.; Lefebvre, E. [CEA, DAM, DIF F-91297 Arpajon (France)
Transitions from the 2p.sup.4 (.sup.1 S.sub.0)3s .sup.2 S.sub.1/2 state of atomic fluorine to all allowed lower states produces laser emission at six new wavelengths: 680.7 .ANG., 682.6 .ANG., 3592.7 .ANG., 3574.1 .ANG., 6089.2 .ANG., and 6046.8 .ANG.. Coherent radiation at these new wavelengths can be generated in an atomic fluorine laser operated as an amplifier or as an oscillator.
Berkowitz, Joseph (Hinsdale, IL); Ruscic, Branko M. (Zagreb, YU); Greene, John P. (Woodridge, IL)
A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.
Moses, E.I.
A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter.
Moses, Edward I. (Livermore, CA)
A high energy gas laser with light output in the infrared or visible region of the spectrum is described. Laser action is obtained by generating vapors of rare earth halides, particularly neodymium iodide or, to a lesser extent, neodymium bromide, and disposing the rare earth vapor medium in a resonant cavity at elevated temperatures; e.g., approximately 1200/sup 0/ to 1400/sup 0/K. A particularly preferred gaseous medium is one involving a complex of aluminum chloride and neodymium chloride, which exhibits tremendously enhanced vapor pressure compared to the rare earth halides per se, and provides comparable increases in stored energy densities.
Krupke, W.F.
Transitions from the 2p/sup 4/(/sup 1/S/sub 0/)3s /sup 2/S/sub 1/2/ state of atomic fluorine to all allowed loser states produces laser emission at six new wavelengths: 680.7A, 682.6A, 3592.7A, 3574.1A, 6089.2A, and 6046.8A. Coherent radiation at these new wavelengths can be generated in an atomic fluorine laser operated as an amplifier or as an oscillator.
Berkowitz, J.; Ruscic, B.M.; Greene, J.P.
A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.
Hackel, Richard P. (Livermore, CA)
A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.
Hackel, R.P.
Single element laser beam shaper
A single lens laser beam shaper for converting laser beams from any spatial profile to a flat-top or uniform spatial profile. The laser beam shaper includes a lens having two aspheric surfaces. The beam shaper significantly simplifies the overall structure in comparison with conventional 2-element systems and therefore provides great ease in alignment and reduction of cost.
Zhang, Shukui (Yorktown, VA); Michelle D. Shinn (Newport News, VA)
Laser Phase Errors in Seeded Free Electron Lasers
Harmonic seeding of free electron lasers has attracted significant attention as a method for producing transform-limited pulses in the soft x-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and may degrade the pulse quality and impede production of transform-limited pulses. In this paper we consider the effect of seed laser phase errors in high gain harmonic generation and echo-enabled harmonic generation. We use simulations to confirm analytical results for the case of linearly chirped seed lasers, and extend the results for arbitrary seed laser envelope and phase.
Ratner, D.; Fry, A.; Stupakov, G.; White, W.; /SLAC
Kinetic Controls on Cu and Pb Sorption by Ferrihydrite
nd ed.; Cambridge University Press: New York, 1993. (51) Sparks, D. L. Kinetics of Soil Chemical Processes; Academic Press: New York, 1989. (52) Espenson, J. H. Chemical Kinetics and Reaction Mechanisms, 2Kinetic Controls on Cu and Pb Sorption by Ferrihydrite A N D R E A S C . S C H E I N O
Sparks, Donald L.
Kinetic and stationary point-set embeddability for plane graphs
Science Conference Proceedings (OSTI)
We investigate a kinetic version of point-set embeddability. Given a plane graph G(V,E) where |V|=n, and a set P of n moving points where the trajectory of each point is an algebraic function of constant ... Keywords: kinetic algorithm, kinetic graph drawing, plane graph, point-set embeddability
Zahed Rahmati; Sue H. Whitesides; Valerie King
Ablative fast pyrolysis of biomass in the entrained-flow cyclonic reactor at SERI
Progress with the entrained flow cyclonic reactor at SERI is detailed. Feedstocks successfully used include wood flour and fairly large sawdust. Preliminary results show that relatively complete vaporization of the biomass is realized and that the yields of tar or gas can be varied over quite a range with trends following first order kinetic concepts.
Diebold, J.; Scahill, J.
Asphalt Oxidation Kinetics and Pavement Oxidation Modeling
Most paved roads in the United States are surfaced with asphalt. These asphalt pavements suffer from fatigue cracking and thermal cracking, aggravated by the oxidation and hardening of asphalt. This negative impact of asphalt oxidation on pavement performance has not been considered adequately in pavement design. Part of the reason is that the process of asphalt oxidation in pavement is not well understood. This work focused on understanding the asphalt oxidation kinetics and on developing pavement oxidation model that predicts asphalt oxidation and hardening in pavement under environmental conditions. A number of asphalts were studied in laboratory condition. Based on kinetics data, a fast-rate ? constant-rate asphalt oxidation kinetics model was developed to describe the early nonlinear fast-rate aging period and the later constant-rate period of asphalt oxidation. Furthermore, reaction kinetics parameters for the fast-rate and constant-rate reactions were empirically correlated, leading to a simplified model. And the experimental effort and time to obtain these kinetics parameters were significantly reduced. Furthermore, to investigate the mechanism of asphalt oxidation, two antioxidants were studied on their effectiveness. Asphalt oxidation was not significantly affected. It was found that evaluation of antioxidant effectiveness based on viscosity only is not reliable. The asphalt oxidation kinetics model was incorporated into the pavement oxidation model that predicts asphalt oxidation in pavement. The pavement oxidation model mimics the oxidation process of asphalt in real mixture at pavement temperatures. A new parameter, diffusion depth, defined the oxygen diffusion region in the mastic. A field calibration factor accounted for the factors not considered in the model such as the effect of small aggregate particles on oxygen diffusion. Carbonyl area and viscosity of binders recovered from field cores of three pavements in Texas were measured and were used for model calibration and validation. Results demonstrated that the proposed model estimates carbonyl growth over time in pavement, layer-by-layer, quite well. Finally, this work can be useful for incorporating asphalt oxidation into a pavement design method that can predict pavement performance with time and for making strategic decisions such as optimal time for maintenance treatments.
Jin, Xin
Laser-Material Interactions: A Study of Laser Energy Coupling with Solids
1971) Effects of High-Power Laser Radiation, Academic Presin Effects of High-Power Laser Radiation, (Academic Press,for modeling gas discharge lasers", Boulder, Colo. : Univ.
Shannon, M.A.
Free-electron laser driven by the LBNL laser-plasma accelerator
OF AN XUV FEL DRIVEN BY THE LASER-PLASMA ACCELERATOR AT THEFree-electron laser driven bythe LBNL laser-plasma accelerator C. B. Schroeder ? , W. M.
Schroeder, C. B.
Laser Triggered Injection ofElectrons in a Laser Wake?eld Accelerator with the CollidingAn injection scheme for a laser wake?eld accelerator that
Development of high damage threshold optics for petawatt-class short-pulse lasers
Science Conference Proceedings (OSTI)
The authors report laser-induced damage threshold measurements on pure and multilayer dielectrics and gold-coated optics at 1053 and 526 nm for pulse durations, {tau}, ranging from 140 fs to 1 ns. Damage thresholds of gold coatings are limited to 500 mJ/cm{sup 2} in the subpicosecond range for 1053-nm pulses. In dielectrics, qualitative differences in the morphology of damage and a departure from the diffusion-dominated {tau}1/2 scaling indicate that damage results from plasma formation and ablation for {tau}{le}10 ps and from conventional melting and boiling for {tau}>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in quantitative agreement with both the pulsewidth and wavelength scaling of experimental results.
Stuart, B.C.; Perry, M.D.; Boyd, R.D. [and others
Behavior of fluid instabilities in laser fusion pellets: results of 2-D calculations
Two-dimensional Lagrangian hydrodynamics simulation techniques were used to study fluid instability in laser fusion pellets. A slab geometry comparison with classical Rayleigh-Taylor theory shows good agreement, as do other slab and spherical test problems over a wide range of accelerations and wavelengths. Isentropic ablative accelerations exhibit growth rates 50 percent-100 percent of classical values, while non-isentropic cases show suppressed growth. Design optimization at 100 kJ input energy has led to an impulsively accelerated, low- aspect-ratio shell which operates successfully with a surface perturbation of a few tens of angstroms. Comparison of simulations with present experiments indicates that current neutron-producing targets are insensitive to damage from fluid instability. (auth)
Mead, W.C.; Lindl, J.D.
Laser-Generated Shockwaves for the Disruption of Bacterial Biofilms
Characterization by modified Laser Spallation Technique (The Basic Laser Spallation Technique (Modified Laser Spallation Technique: �Top-Down�
Navarro, Artemio
Applications of Nd:YAG laser micromanufacturing in High Temperature Gas Reactor research
Two innovative applications of Nd:YAG laser micromachining techniques are demonstrated in this publication. Research projects to determine the fission product transport mechanisms in TRISO coated particles necessitate heat treatment studies as well as the manufacturing of a unique sealed system for experimentation at very high temperatures. This article describes firstly the design and creation of an alumina jig designed to contain 500 {mu}m diameter ZrO2 spheres intended for annealing experiments at temperatures up to 1600 C. Functional requirements of this jig are the precision positioning of spheres for laser ablation, welding and post weld heat treatment in order to ensure process repeatability and accurate indexing of individual spheres. The design challenges and the performance of the holding device are reported. Secondly the manufacture of a sealing system using laser micromachining is reported. ZrO2 micro plugs isolate the openings of micro-machined cavities to produce a gas-tight seal fit for application in a high temperature environment. The technique is described along with a discussion of the problems experienced during the sealing process. Typical problems experienced were seating dimensions and the relative small size ({approx} 200 {mu}m) of these plugs that posed handling challenges. Manufacturing processes for both the tapered seating cavity and the plug are demonstrated. In conclusion, this article demonstrates the application of Nd-YAG micromachining in an innovative way to solve practical research problems.
I. J. van Rooyen; C. A. Smal; J. Steyn; H. Greyling
Crater effects on H and D emission from laser induced low-pressure helium plasma
Science Conference Proceedings (OSTI)
An experimental study has been performed on the effects of crater depth on the hydrogen and deuterium emission intensities measured from laser plasmas generated in low-pressure helium ambient gas from zircaloy-4 samples doped with different H and D impurity concentrations as well as a standard brass sample for comparison. The results show that aside from emission of the host atom, the emission intensities of other ablated atoms of significantly smaller masses as well as that of the He atom generally exhibit relatively rapid initial decline with increasing crater depth. This trend was found to have its origin in the decreasing laser power density arriving at the crater bottom and thereby weakened the shock wave generated in the crater. As the crater deepened, the declining trend of the intensity appeared to level off as a result of compensation of the decreasing laser power density by the enhanced plasma confinement at increasing crater depth. Meanwhile, the result also reveals the significant contribution of the He-assisted excitation process to the doped hydrogen and deuterium emission intensities, leading to similar crater-depth dependent variation patterns in contrast to that associated with the surface water, with growing dominance of this common feature at the later stage of the plasma expansion. Therefore, a carefully chosen set of gate delay and gate width which are properly adapted to the crater-depth dependent behavior of the emission intensity may produce the desired intrinsic emission data for quantitative depth profiling of H impurity trapped inside the zircaloy wall.
Pardede, Marincan; Lie, Tjung Jie; Kurniawan, Koo Hendrik [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Niki, Hideaki; Fukumoto, Kenichi [Program of Nuclear Power and Energy Safety Engineering, Graduate School of Engineering, Fukui University, Fukui 910-8507 (Japan); Maruyama, Tadashi [Integrated Research Institute, Tokyo Institute of Technology, 4259 Nagatsuda-cho, Midori-ku, Yokohama 226-8503 (Japan); Kagawa, Kiichiro [Department of Physics, Faculty of Education and Regional Studies, Fukui University, 9-1 bunkyo 3-chome, Fukui 910-8507 (Japan); Tjia, May On [Physics of Magnetism and Photonics Research Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)
that are applicable at the molecular level. Copyright # 2004 John Wiley & Sons, Ltd. KEYWORDS: kinetic stability of that system are undergoing constant change. This chemical example of replicator kinetic stability is akin in circumstance may dramatically affect the kinetic stability of physical, chemical and biological, systems. So
Hille, Sander
React. Kinet.Catal.Lett., Vol.9, No. 4,377-381 (1978) WHAT IS ESSENTIAL TO EXOTIC KINETIC BEHAVIOR?
6= 10'. I = 1 I=I 378 #12;TOTH: EXOTIC KINETIC BEHAVIOR? COROLLARIES Immediate application). REFERENCES 1. M. Feinberg: Mathamatical Aspects of Mass Action