An array for achromatic imaging of a pulsed beam of charged particles is described. The device comprises an imaging system with a round lens optics (2, 7), a low-energy drift space (3) and an accelerator (4-6) driven by at least one rapidly switchable voltage U(t), such that the velocity and/or trajectory of the particles in the beam is influenced and the particles starting from point (1) with different energies are crossing the image plane in one point (8), i.e. the chromatic aberration of the optics is compensated.

This application claims Priority from German Application No. DE 102 17 507.1 filed on Apr. 19, 2002.
The present invention describes an array imaging a pulsed particle beam emitted from at least one point on a sample on to a detector.
It is known that so-called particle lenses, i.e. lenses for charged particles like electrons can influence the paths of these particles in a similar way as an optical lens influences photon rays.
Such particle lenses are applied e.g. in electron microscopes. The chromatic and spherical aberrations of particle lenses are the main factors limiting spatial resolution. Astigmatism is the result of misalignment and can be compensated by electric or magnetic stigmators and correcting image curvature which is often of secondary importance. However, the chromatic and spherical aberrations constitute a basic problem for all optical systems composed of round lenses.
The chromatic aberration is caused by the different energies of the particles in the beam and results in the fact that particles of different energy do not intersect the ideal image point. In other words: due to the chromatic aberration particles with different energy hit the image plane in different positions.
In contrast to photon optics these aberrations cannot be corrected by suitable lens combinations. The reason is that, independent of type and geometry of the selected lens, all particle optical round lenses are characterized by spherical and chromatic aberration coefficients c, and cc, respectively, that are always positive. Thus, the combination of lenses with coefficients with different sign in a lens system of round lenses is impossible.
This fundamental property of all optical round lenses for particles is known as Scherzer""s theorem [O. Scherzer, Z. fxc3xcr Physik 101 (1936) 593].
Scherzer [O. Scherzer, Optik 2, 115 (1947)] and other authors have searched for ways to circumvent this theorem and discussed different possibilities for the correction of c, and cc.
An overview is given by Hawkes and Kasper [Principles of Electron Optics, Academic Press 1996, Vol. 2, p. 857ff]. The conditions for the validity of Scherzer""s theorem are: round lenses, real images, static fields, no space charge, no potential jumps. These conditions imply possibilities to circumvent the theorem. Despite numerous attempts with different methods, only the use of multipole correctors in high-resolution transmission electron microscopes has been successful up to now [M. Haider, S. Uhlemann, B. Schwan, H. Rose, B. Kabius, K. Urban, Nature 392 (1998) 768]. A second possibility of aberration correction by means of electron mirrors was proposed and is being tested [G. F. Rempfer et al., Microsc. Microanal. 3 (1997) 14; R. Fink et al., Journal of El. Spectrosc. Relat. Phenom. 84 (1997) 231]. These methods pose a high challenge on the mechanical precision and the current or voltage stability of the electronics. In addition, the adjustment is very demanding, in particular in the case of the non-linear optical axis connected with the solution of the electron mirror.
Several authors discussed the application of so-called high-frequency lenses [Hawkes and Kasper, Principles of Electron Optics, Academic Press 1996, Vo., 2, p. 872 ff], where the lens is formed by a micro wave resonator or the resonator is integrated into a lens. It turned out that the phase condition (i.e., the relation between the phase of the micro wave and the phase of the electron bunch when entering the resonator) and the dwell time in the resonator plays a crucial role. None of the proposals in connection with high-frequency lenses has been realized successfully.
In reference (U.S. Pat. No. 5,196,708 A) a particle source is described that produces a pulsed particle beam in a way that the particles belonging to a bunch experience a pulsed electrical field in a so-called xe2x80x9cbuncherxe2x80x9d synchronized with the pulses. This pulsed electrical field causes an acceleration of the electrons at the end of the bunch. This acceleration causes a desired shortening of the axial expansion of the particle formation. This axial compression can be used for imaging with reduced chromatic aberration. This energy focussing effect using a pulsed axial electrical field is also known from time-of-flight mass spectroscopy (Rev. Sci. Instr. 26(1955) 12, 1150-7 (Wiley. W.C.: McLaren. I.H.), section on time-lag energy focussing, p. 1154. The reduction of flight-time differences by pulsed fields can also be exploited for an improvement of the mass resolution of a time-of-flight mass spectrometer. (DE 44 42 348 A1). These methods cause a temporal and spatial compression of the particle ensemble at the target (called bunching effect in reference U.S. Pat. No. 5,196,708 A).
The contribution of the chromatic aberration to the total resolution of an optical system is given by
xcex4c=ccxcex1xcex94E/E
where cc is the chromatic aberration coefficient dependent on lens geometry and energy, xcex1 is the beam pencil angle accepted by the contrast aperture and xcex94E/E is the relative width of the energy distribution of the imaged charged particles with centre of gravity at energy E.
It is an object of the present invention to provide a device that enables correction of the chromatic aberration of a system of round lenses for charged particles, but wherein the complexity of the arrangement is greatly reduced. This is achieved via energy dependent axial expansion, i.e. energetic dispersion, of the pulsed particle beam in a low-energy drift space.
According to a first aspect of the present invention, an arrangement for imaging of a pulsed particle beam from a sample to a detector with minimized chromatic aberration comprises: an imaging system with particle optical round lens optics, a low-energy part of the optics called drift space, means for application of a rapidly switched voltage such that the velocity of the particles of the beam is changed in a way that the particle rays starting in one point on the sample intersect the image plane in one point thus leading to a reduction of the chromatic aberration in the image. To achieve this, the fastest particles reach the end of the drift space before the switching of the electrical field and are thus not influenced by the field. The slower particles, however, are accelerated by the application of a suitable voltage in a way that the energy gain is proportional to the local potential in the moment when the voltage is switched on. Their energy gain is the higher, the slower the particle has been on its way through the round lens optics. This means that the particles at the front of the beam retain their energy, whereas the particles in the centre of the beam gain a higher kinetic energy and the particles at the end of the beam gain the highest kinetic energy.
The energy distribution of the particle beam can be inverted if a parabolic potential is applied. As the originally fastest particles retain their velocity or energy, however the slowest particles are also accelerated to a new energy higher than the originally fastest particles, the chromatic aberration of the following round lens optic can compensate the chromatic aberration of the preceding part of the optics. The particles are intersecting in the same image point, i.e. the total chromatic aberration vanishes in the sense that all particle rays intersect in the ideal image point. This implies that the voltage has to be switched in the moment when the particle beam is in the accelerator at the end of the drift space. Further advantages are described in the claims.
According to a special embodiment of this first aspect of the invention, the particles in a particle beam can be decelerated by a retarding voltage and dispersed in a subsequent low-energy drift space such that the distance between particles with different energies is increased. This deceleration of the particles by means of the to retarding voltage retains the velocity differences between the different particles but reduces the average velocity of the beam. Hence, electrons with different velocities gain distance from each other. Behind the drift space the particles experience an energy increase in the pulsed accelerator such that the slower particles gain more velocity than the faster ones. Consequently, all particle rays intersect in the ideal image point leading to a vanishing chromatic aberration as described above.
According to a second aspect of the present invention, an arrangement for imaging of a pulsed particle beam from at least one point of several points on a sample comprises: an imaging system with particle optical round lens optics, a low-energy drift space increasing the spatial and temporal distance between the particles of the particle ensemble with different velocities such that after passing of the particles through the drift space the refractive power of the round lens optics behind the drift space is adapted at each moment such that the focal width of the optics remains the same for all particle energies and such that all particle energies of the beam are imaged with the same magnification on the screen. Consequently, the chromatic aberration is eliminated in the image.
Further advantages of this second aspect of the present invention are described in the claims.
The visualization of the particle-optical image requires a detector. Such a detector can comprise a fluorescent screen and a CCD-camera that acquires the image. Alternatively, the detector can be designed such that all particles are individually detected and registered with respect to their spatial coordinate and arrival time on the detector. This bears a number of advantages: it provides the mode of energy-resolved imaging of the particles or the possibility of imaging of selected particle energies such that the partial images corresponding to different energies can be adjusted in scale resulting in a sharp image. The adjustment of the partial images taken at different energies to the same scale requires compression, expansion, rotation or displacement of each partial image by means of suitable image acquisition software. Furthermore, this procedure allows compensating the influence of spurious stray fields.
Of particular advantage is the application of both aspects of the present patent in an arrangement imaging pulsed particle beams emitted from a sample in an electron or an ion microscope or in optics for projection lithography. It can also be exploited in the generation of pulsed electron or ion microprobes.

Array for achromatic imaging of a pulsed particle beam


A toothbrush design which more effectively permits bristle penetration into the spaces between tooth and gum for removal of plaque and food debris lodged within these spaces. The toothbrush design incorporates a rotatable brush disc having a plurality of radially outward extending bristles but where the width of the bristle disc and number of bristles are preferably limited so that the bristle tips can penetrate into the space between tooth and gum and preferably be of sufficient length to penetrate to the bottom of the space.

This invention relates to the field of dental hygiene.
Many individuals suffer from periodontal disease. The term xe2x80x9cperiodontalxe2x80x9d is generally defined as the area around the tooth. This includes the gum, periodontal membrane and bone tissue holding a tooth in place. If periodontal disease is diagnosed, dental surgery is typically required to correct the gum condition. Following surgery, it is necessary to keep the space, or sulcus, between the teeth and gum clean. This is critical for successful healing and improving the gum to a healthy condition.
The healing process following periodontal surgery is critical. Typically, immediately following surgery, the sulcus is filled with temporary protective packing for approximately one to two weeks. Gum swelling resulting from surgery has, after this period of time, subsided to the point where tooth brushing can begin. Dental plaque and food debris must thereafter be kept to a minimum in the sulcus for the gums to continue to heal correctly.
Good oral hygiene for gum healing is one of the most effective dental prophylaxes. For this reason, it is critical to obtain an effective penetration of the toothbrush bristle tips into the sulcus.
To properly clean the sulcus, many experts recommend that the bristle tips must reach to the bottom of the sulcus in order to remove all debris and plague.
Commonly known among dentists is the Bass Method, a method for properly brushing the tooth and sulcus. The Bass Method is considered the most efficient tooth brushing technique yet most people are either not familiar, or simply don""t know how to properly perform.
Most individuals tend to brush only the prominent tooth surfaces, which are usually self-cleaned simply by eating fibrous foods such as meats and vegetables.
Proper use of the Bass Method requires a portion of the bristle tips to be in contact and thereafter movement of the toothbrush with a short back-and-forth motion without dislodging the tip of the bristles from their contact.
The Bass Method could be more efficiently implemented if a user could insert at least a few of the toothbrush bristle tips to the bottom of the sulcus. Unfortunately, the conventional toothbrush is not designed for its bristles to penetrate completely into the space between the tooth and gum.
Specifically, the conventional toothbrush typically has an excessive bristle surface area making it extremely difficult for individuals to position the bristles for penetration into the sulcus.
Typical toothbrushes are used to sweep their bristles back and forth across the surfaces of tooth and gum in proplylaxis. In other words, the bristles slide over small spaces between teeth and between the tooth and gum. This bristle action, because of it sliding over the spaces, actually passes over plaque and food debris, or can even force such material deeper into the space.
When a toothbrush is used in this conventional manner, the bristle tips are not properly positioned to be inserted into, nor do they have the necessary contact time within the sulcus to effectively remove plaque and food debris.
The present invention introduces a new technique and toothbrush design, which permits necessary bristle penetration into the sulcus for effective removal of plaque and food debris lodged within these spaces.
Rather than sweeping the bristles across the tooth and gum, my modified toothbrush comprises an elongated body defining a handle which connects to a rotatable brush disc. The brush disc includes a plurality of radially outward extending bristles. The width of the bristle disc and number of bristles are limited so that an effective number of the bristle tips present on the disc can, when properly positioned, penetrate into the space between tooth and gum and preferably be of sufficient length to penetrate to the bottom of the sulcus.
It is not necessary that the bristles"" width i.e. the number of bristles across the bristle disc, be limited to only the width of the space between tooth and gum. What is necessary is that the overall design of the toothbrush permits a user to easily and efficiently insert a sufficient number of bristles into the sulcus for cleaning.
In preliminary testing which preceded my final design, a standard toothbrush was modified; specifically, reducing the number of bristles by reducing the bristle surface area. The surface area was reduced so that bristle tips could be more easily inserted into the sulcus. However, patients found it difficult to implement the technique of inserting the bristles into the small space between the tooth and gum.
Further, the modified toothbrush could function properly only when the integrity and alignment of the bristles which penetrate into the sulcus were maintained in a substantially straight and rigid form during the application of the pressured strokes of the Bass Method described above.
In order to function properly, the bristle tips penetrate to the base of the sulcus. Short strokes are then used while the bristle tips are engaging or digging into the gum located at the base of the sulcus so that the bristle tips do not dislodge. After completion of the strokes, the brush is first moved vertically so the tips dislodge, then moved across to an adjacent area and the same procedure is repeated. A more detailed description of this method now follows:
A toothbrush is held using a grip at two points on the brush handle. One point would be the midpoint on the backside of the brush handle, which would be pressed with the index finger. The second point would be on the front side of the handle (same side as the bristles), which would rest against the palm of the hand. With the bristles resting on the gum-line and slight pressure applied on these two points, when minimal back and forth motion is applied, the toothbrush will be secure enough in the hand of the user to make the bristles penetrate into the small gum spaces.
While the intended results were obtained, the required brushing instructions again turned out to be difficult to follow.
Based on the difficulties associated with using bristles rigidly affixed to a brush head to clean the spaces between tooth and gum, a toothbrush was designed which is easy to orientate to the correct cleaning position and provide an effective cleaning of the space between tooth and gum.
The brush design can be incorporated for both manual and electric toothbrushes. This invention can be efficiently used as an attachment to an electric toothbrush. The strokes generated by the electric toothbrush would drive the bristles of the rotary disc or bristle wheel into the sulcus. Bristle tips are designed to conform or adapt to the shape of the tooth and gum using the motion of the strokes generated by the electric toothbrush.
The brush design can also incorporate either single or dual rotary discs, which will be discussed below. Finally, each design can also include a separate set of bristles for the conventional brushing technique of sweeping across the tooth surface, as found on a standard toothbrush.
The present invention cleans not only the tooth surface and interproximal portion between the teeth, but also facilitates the healing of simple gingivitis (minor gum inflammation). And unlike the bristles found on a conventional toothbrush which are dragged across the tooth surface in a back and forth, and up and down motion; my rotary toothbrush is designed so that an effective number of bristle tips can penetrate into the sulcus.
My design incorporates bristles that extend radially outward from a disc rotatably mounted to a toothbrush handle.
A. Single Rotary Bristle Design
When positioned properly, rotary bristles are inserted into the sulcus. Once in position, the user slowly moves the brush in a substantially horizontal direction while maintaining a constant downward force on the toothbrush so that the bristle tips will reach to the base of the sulcus. Once in position and while maintaining sufficient force on the bristle tips to keep them in contact with the gum at the base of the sulcus, short strokes are then applied.
Afterwards, rather than lifting the bristle tips by vertically moving the toothbrush, the downward force which was applied is now released and the toothbrush is displaced in a substantially horizontal direction so that the bristle disc rotates so that different bristle tips will be in position for engagement with the base of the sulcus. As the toothbrush is moved, the bristle disc also will rotate and impart a cleaning force to dislodge the debris and carry it up above the gum line.
By taking into account that bristles must be able to penetrate into the sometimes abnormally deep sulcus formed by the tooth and gum it is envisioned that many new toothbrush designs can be developed based upon my rotatable disc design.
B. Dual Rotary Bristle Design
One design alternative is to use a dual bristle disc design. While one bristle disc is in position to clean the gum and teeth, the second disc is sufficiently spaced from the other. Disc spacing can help to maintain a proper angle, linear direction and position of the first disc while simultaneously cleaning the top surface of the teeth with the second disc.
Use of a rotary disc design, either single or dual, permits the bristle tips, provided they have the appropriate length, to penetrate into the deepest regions of the sulcus between tooth and gum, while allowing the discs to rotate freely when the toothbrush is moved for cleaning an adjacent area.
The bristles extending from the bristle disc can conform to the adjacent shape of the tooth and gum, so that the bristle disc within the sulcus can freely rotate according to the resistance met by the downward force applied to the bristles in contact with the gum at the base of the sulcus. The bristle tips can reach the deepest area between tooth and gum because of my new design which orientates bristles for insertion into the sulcus rather than for perpendicular contact with the tooth surface.
Because perpendicular contact with the tooth surface is minimized, this diminishes the bristle resistance associated with the tooth surface, and, as a result, more bristles are available for penetration into the surrounding crevices and spaces, and actively dig and remove food debris and other substances from the deep spaces of the sulcus.
As mentioned earlier, my invention can incorporate a second set of bristles; these being the traditional toothbrush bristles located on the side of the disc, extending in a perpendicular direction away from the bristle disc. This second set can be used to brush and polish the prominent tooth surfaces.
Some of the objectives of my invention can be summarized as follows:
To design a toothbrush having a rotatable brush disc that will work along the gingival crevice by means of a linear rolling motion;
To design a toothbrush having a rotatable bristle disc which is free from the dragging force of the bristles during brushing;
To design a toothbrush where the bristle tips associated with the toothbrush could penetrate deep into the sulcus, contact the base of the gum and not be dislodged during the implementation of short cleaning strokes;
To design a toothbrush that incorporates a small bristle tip surface area on the plurality of rotary extending bristles for easy penetration of the bristle tips into the sulcus.


The present invention provides a method of processing organic waste (D) in divided solid and/or liquid form, the method being implemented in a single reactor (1) containing a bath of molten glass (V) surmounted by a gas phase (G), the method comprising incinerating said waste (D) in the presence of oxygen at the surface (S) of said bath of molten glass (V), and in vitrifying said incinerated waste (D) in said bath of molten glass (V). In said method, and in characteristic manner, in addition to the oxygen delivered as oxidizer into said gas phase (G), oxygen is also injected into said bath of molten glass (V) in a quantity that is sufficient to minimize or to avoid any formation of metal within said bath of glass (V); advantageously in a quantity that is sufficient to minimize or to avoid any formation of metal within said bath of glass (V) and also to subject said bath of glass (V) to moderate stirring. The present invention also provides apparatus for processing organic waste (D) in divided solid and/or liquid form by incineration and vitrification, the apparatus being suitable for implementing said method.

The present invention relates to a method and to apparatus for incinerating and vitrifying waste, in particular radioactive waste.
Said invention lies within the context of processing dangerous combustible waste for which it is appropriate to fix the ash in stable manner. To neutralize waste of that type, it has long been the practice to operate in two stages, each of said stages being implemented in an independent apparatus:
a first step of incinerating said organic waste, in divided solid and/or liquid form, in an incinerator apparatus; and
a second stage of fixing the ash recovered from said first stage, said second stage being implemented in suitable apparatus that contains a bath of glass maintained in the molten state.
Nevertheless, for several years, waste processing methods have been described in which said two stages of incinerating said waste and fixing the resulting ash have been implemented in a single apparatus. In this context, a term that is used is xe2x80x9cdirect vitrificationxe2x80x9d.
Results obtained in said context by the Applicants have been described in particular at the xe2x80x9cKorean Atomic Industrial Forumxe2x80x9d (KAIF) ""98, which was held Apr. 14 to 17, 1998 in Seoul, South Korea. Said results demonstrated the feasibility of a direct vitrification method, in which the waste is burned for the most part at the surface of a bath of molten glass, in an oxidizing atmosphere, with the ash that is generated being trapped and fixed in said bath of molten glass; since said method was implemented in a cold crucible, said bath of molten glass was heated by induction.
Continuing their work on direct vitrification, the Applicants have designed and developed the present invention which can be considered as being an improvement of said direct vitrification as presently known. The improvement which constitutes the main subject matter of the present invention can be thought of both in terms of a method and in terms of apparatus, and it involves the quality of the bath of glass. Said improvement which, in order to clarify the present description, can be referred to as the xe2x80x9cmainxe2x80x9d improvement, is advantageously implemented with other improvements that, in the same spirit, can be referred to as xe2x80x9csecondaryxe2x80x9d improvements. Said main and secondary improvements are described below in general terms and then in greater detail with reference to the accompanying figures.
Thus, in a first aspect, the present invention provides a method of processing organic waste (i.e. combustible waste) in divided solid form (to facilitate insertion and combustion) and/or in liquid form, the method being implemented in a single reactor containing a bath of molten glass surmounted by a gas phase; said processing method comprising: incinerating said waste in the presence of oxygen at the surface of said bath of molten glass (said waste falling onto said surface, decomposing thereon, and the resulting gaseous products of said decomposition being burned in said oxygen-containing gas phase); and vitrifying said incinerated waste in said bath of molten glass. In this respect, the method of the invention is a direct vitrification method.
In characteristic manner, said method further comprises injecting oxygen into said bath of molten glass, in sufficient quantity to minimize or to avoid any formation of metal within said bath of glass; advantageously, in sufficient quantity to minimize or to avoid any formation of metal within said bath of glass and to subject bath of glass to moderate stirring.
Said oxygen which is introduced in original manner into the bath of molten glass is introduced into the process reactor in addition to the oxygen being delivered in conventional manner as oxidizer into the gas overlying said bath, in order to ensure that the waste is incinerated.
In characteristic manner, in the context of the method of the invention, not only does said oxidizer in the gas phase react, but so also does the oxygen within the bath of glass, said oxygen serving to adjust the oxidation-reduction (redox) potential of said bath of glass (thus serving to limit the reducing nature of the glass).
By controlling the redox potential of the bath of glass in this way, it is possible within said bath of glass to prevent oxides being reduced and thus to prevent metals being formed. The presence of such metals within said bath is very harmful to the uniformity of said bath, and thus to the quality of the vitrification obtained. In addition, the presence of metal can give rise to real difficulties when performing heating by induction . . . .
The oxygen injected into the bath of glass to minimize or even to avoid the formation of metal is advantageously injected in sufficient quantity also to ensure that said bath of glass is stirred somewhat. The person skilled in the art knows how to optimize the quantity of oxygen required for these purposes. In any event, the quantity must be sufficient to obtain the desired effect concerning the value of the redox potential, and indeed the desired effects concerning the value of said potential and also the looked-for stirring effect, but it must not be excessive, insofar as the bath of glass while being stirred and mixed must nevertheless remain a bath of glass and must not be transformed into a foam . . . .
Oxygen has been mentioned as the oxidizer involved in the gas and as the oxidant gas introduced into the bath of glass, and this is appropriate insofar as said oxygen is generally delivered as a xe2x80x9cpurexe2x80x9d gas. Nevertheless, it is not entirely beyond the scope of the present invention to use a gas that contains oxygen, and in particular to use air, optionally enriched in oxygen, as the oxidizer and as the oxidant gas.
The oxygen delivered as oxidizer into the gas phase is advantageously optimized for the incineration in question, so as to be present in a quantity that is greater than the theoretically required stoichiometric quantity. Advantageously, this oxygen is present in a quantity that lies in the range 1.25 to 1.5 times said stoichiometric quantity. Nevertheless, said quantity is controlled and does not interfere with the negative pressure that is maintained within the reactor in conventional manner for obvious safety reasons. Said negative pressure is maintained by sucking out the combustion gases, where said suction is implemented under conditions such as to minimize the amount of waste, and above all the amount of ash, that is entrained.
Once the principle of the main improvement provided by the invention to the direct vitrification method has been accepted (i.e. the principle of injecting oxygen into the bath of glass), the way in which it is implemented can be subject to several variants, in contexts that are somewhat different.
In particular, the method of the invention can be implemented with a bath of glass that is practically pre-constituted (i.e. present in the reactor before the waste is introduced therein), or with a bath of glass that is constituted progressively from some minimum initial fill. In this second variant, which is preferred, the reactor starts by containing an initial bath of glass that is of small volume (a starter) and it is subsequently fed both with waste and with substances for forming a bath of glass. Said waste and said glass-forming substances are also advantageously introduced as a mixture . . . with the waste being treated as one of the precursors of substances for making said bath of glass. The reactor is thus fed continuously with waste and with substances for forming the bath of glass, and indeed with additives therefor. Once a certain level has been reached, both types of feed are stopped and the resulting bath of glass can be emptied out.
In a preferred variant implementation of the method of the invention, the oxygen which is injected into the bath of glass is introduced into the reactor beneath the surface of said bath of glass. Thus, the means for injecting said oxygen do not pass through the gas phase in said reactor, and are therefore subject to one type of corrosion only: the corrosion inherent to said bath of glass.
This type of comment applies to any device that is to penetrate into said bath of glass in order to deliver any substance (injecting oxygen has just been mentioned) or to measure any parameter therein (such as temperature, redox potential, . . . ). Thus, any device for penetrating into said bath of glass is advantageously introduced into the reactor from beneath the surface of said bath of glass so as to avoid coming into any contact with the gas phase.
There follows a general description in method terms of the secondary improvements of the present invention.
The method of the invention which comprises injecting oxygen into the bath of glass is advantageously implemented together with cooling of the walls of the reactor and/or, preferably, of the means introduced into said reactor, both in said gas phase and in the bath of glass, which means are introduced in particular for feeding said reactor with the waste to be incinerated and vitrified, for feeding the reactor with oxygen both in its gas phase (said oxygen being used as an oxidizer) and in said bath of glass (said oxygen then acting as an oxidant for adjusting the redox potential of said bath of glass and advantageously for stirring purposes).
This list of means that are advantageously cooled is not limiting. For example, it could include means for measuring the temperature of the gas phase, means for measuring the temperature of the bath of glass, means for measuring the redox potential of said bath of glass, means for measuring the level of said bath of glass, . . . .
Such cooling is intended above all to provide said walls and said means with protection from corrosion. It is also appropriate to preserve the sealing devices installed in the passages through said walls.
In the structure of the device for feeding the reactor with waste, it is advantageous to implement dual cooling:
first cooling of the device on its gas phase side (outside face); and
second cooling of the same device, generally independent of the first, on its waste intake side (inside face).
Said first cooling is intended above all to protect said device from the corrosion that occurs due to coming into contact with the gas phase; said second cooling is intended above all to minimize the amount of heat transferred to the incoming waste, in order to minimize vaporizing liquid waste and to avoid solid waste sticking together, since that can lead to the feeder device becoming clogged.
In order to cool the walls of the reactor and the various means that are introduced into said reactor, it is conventional to make use of cooling fluids, generally cooling liquids. Said walls and said means have circuits for circulating such fluids applied thereto. In a particularly preferred variant of implementation of said cooling, provision is made at least in the walls that come into contact with the gas phase and/or at least in the means introduced into the reactor and coming into contact with said gas phase for at least one cooling fluid to circulate, said fluid being maintained at a temperature that is above the dew point of said gas phase. In this advantageous variant, the idea is to prevent any condensation of said gas phase on said walls and on said outside surfaces of said means. The phenomenon of condensation is clearly harmful, given the problems of corrosion. It can also give rise to electric arcing, and can thus raise serious problems when the bath of glass is heated by induction. In this advantageous variant, it is possible to use a xe2x80x9chotxe2x80x9d cooling fluid constituted by superheated water.
The dual cooling referred to above as being advantageously implemented in the device for feeding waste to the reactor is implemented in a particularly preferred variant by using such a xe2x80x9chotxe2x80x9d cooling fluid (at a temperature greater than the due point of the gas phase to which it passes), at least for cooling said device where it is adjacent to the gas phase (the first above-mentioned cooling). Said second cooling beside waste intake can make use of such a xe2x80x9chotxe2x80x9d cooling fluid only when the waste concerned can withstand the temperature of such a xe2x80x9chotxe2x80x9d fluid. As a general rule, said second cooling is implemented with a xe2x80x9ccoldxe2x80x9d cooling fluid, such as water at ambient temperature.
In the method of the invention, in order to heat and maintain the bath of molten glass at a suitable temperature, use can be made of various techniques. Thus, said bath of glass can be heated by induction, by means of a flame, by using a plasma torch, or by means of electrodes dipped into the bath. It is not impossible to use a plurality of said techniques in combination. Induction heating is preferred; induction heating implemented in a cold crucible is most particularly preferred.
The method of the invention as described above and below with reference to the accompanying figures is particularly suitable for processing radioactive waste by direct vitrification.
Said method of the invention is generally implemented with waste being fed in continuously; said waste being introduced above the surface of the bath of glass, possibly mixed with substances suitable for constituting said bath of glass. After a fill has been incinerated and after the ash generated thereby has been digested in the bath of glass, said bath of filled glass is emptied out. Thus, the usual situation is continuous feed (or continuous building up of filler), with emptying out being performed discontinuously.
Nevertheless, in implementing the invention, the following can apply.
The reactor can be fed with waste and oxygen in a manner that is advantageously optimized so as to ensure maximum combustion of said waste while ensuring that the combustion gases entrain a minimum amount of said waste, whether burnt or unburnt. Such optimization relies on combined mastery of numerous parameters, some of which are mentioned above, and in particular mastery of the following:
the size of said waste;
the quantity of oxygen delivered;
the level at which waste is introduced relative to the surface of the bath of glass (advantageously, provision is made to regulate the waste introduction level by regulating the introduction depth of the device for feeding said waste into the reactor); and
the quality of the waste/oxygen mixture, when introducing said waste. Said waste is advantageously introduced while immersed in oxygen. For this purpose, at least one oxygen feed circuit is advantageously included in the structure of the device for feeding said waste.
There follows a description in general terms of the second aspect of the present invention, namely apparatus for processing organic waste in the form of divided solids and/or liquids by incineration and by vitrification; which apparatus is suitable for implementing the above-described method. In conventional manner, said apparatus comprises a reactor, associated firstly with heater means suitable for maintaining a bath of molten glass in the bottom of said reactor, and secondly fitted with the following means:
means for emptying said bath of molten glass;
a device for feeding it with waste to be incinerated and vitrified, said device opening out above the surface of said bath of molten glass and its depth of introduction into said reactor advantageously being adjustable;
oxygen feed means delivering said oxygen above the surface of said bath of molten glass (to implement incineration); and
at least one combustion gas outlet formed in the top portion of said reactor well above the surface of said bath of molten glass (in order to minimize entraining ash).
Said apparatus, in characteristic manner, is also fitted with means for injecting oxygen into said bath of molten glass.
Said means are advantageously introduced into the bottom portion of the reactor, beneath the surface of the bath of glass so that they do not come into contact with the gas phase, thereby being subjected to one type of corrosion only (that developed by the bath of glass).
Said means are also advantageously arranged in such a manner that on ceasing to feed them with oxygen, they do not constitute a plug of glass at their open end. Thus, said means for injecting oxygen into said bath of glass are advantageously disposed vertically through the bottom (of the bottom plate) of the reactor, and provided with an opening disposed at 90xc2x0 to the vertical axis.
The essential elements of the apparatus of the invention, necessary for implementing the intended method of incineration and vitrification are those specified above. Other elements can accompany said elements, for example means for measuring the temperature of the gas phase, means for measuring the temperature of the bath of molten glass, means for measuring the level of said bath of molten glass, means for measuring the level of said bath of glass, means for measuring the redox potential of said bath of molten glass, . . . .
In general terms, it has been found advantageous to cool all of the means that are introduced into said reactor (into the gas phase and into the bath of glass). Thus, in an advantageous embodiment of the apparatus of the invention, all of said means introduced into the reactor, and in particular the device for feeding said reactor with waste, the means for feeding the gas phase with oxygen, and the means for injecting oxygen into said bath of glass, include within their structure at least one circuit for circulating a cooling fluid. Said device for feeding said reactor with waste includes, advantageously embedded in the thickness thereof, at least two generally independent circuits of said type, comprising at least one for cooling its thickness together with its outside surface (in order to minimize problems of corrosion), and at least one other for cooling its inside surface (in order to transfer a minimum amount of heat to the incoming waste). Said feeder device generally presents a tubular structure which is defined by an inside surface and an outside surface.
With reference to said feeder device, it can also have the following additions. It advantageously includes in its structure means for conveying and delivering oxygen to its open end (above the bath of glass). Delivery of said oxygen can be provided in particular by means of a torus arranged around the open end of said device, said torus being pierced by suitable orifices, appropriately distributed. Contact between the waste and the oxygen (oxidizer) can thus be optimized.
The inlets and outlets for the cooling fluids advantageously circulated through the structure of the device for feeding the reactor with waste, and also through the oxygen inlet, likewise advantageously circulated through said structure, are connected to appropriate delivery and removal units. The distribution of said fluids and said oxygen in their respective circulation circuits within said feeder device is advantageously organized by means of a set of distribution chambers and channels, suitably arranged.
Advantageously, the reactor is also cooled. Its walls are advantageously of the double-walled type, so as to allow a cooling fluid to circulate therein.
The heater means associated with said reactor can be of various types, and in particular can be suitable for implementing induction heating, flame heating, plasma torch heating, or heating by means of immersed electrodes. In a particularly preferred variant embodiment, the reactor used is a cold crucible and said heater means are induction heater means.

Method and device for incineration and vitrification of waste, in particular radioactive waste

Societe General pour les Techniques Nouvelles - SGN


In the process for recovering carbon disulfide from a steam/carbon disulfide mixture, which is produced when the wastewater from the yarn cutters and the suspension water are treated with steam during the manufacture of viscose rayon, the vapors so produced are cooled by means of a liquid spray, drawn out of the vapor condenser and then condensed. The non-condensable constituents are removed via a trap and the liquefied carbon disulfide is separated from the remaining water. Specifically, the liquid used to spray the vapors is preheated by the thermal energy recovered from the cooling of these vapors, and the hot water thus obtained is then used for other purposes.

The present invention concerns a process for the recovery of carbon disulfide from a steam/carbon disulfide mixture which is produced, in particular, in the manufacture of viscose rayon when the wastewater from the yarn cutters and the suspension water are treated with steam.
The wastewater from the yarn cutters and the suspension water produced in the manufacture of viscose rayon are diverted into a trough where they are collected. In this collection trough, said waste water is treated with steam at temperatures of approximately 98.degree. C. The steam/CS.sub.2 mixture so generated is then drawn off.
It is known that carbon disulfide is recovered from the steam/CS.sub.2 mixture by using a heat-exchanging process to condense the steam, after which the carbon disulfide contained in the steam is obtained through subsequent cooling to the point of condensation.
In the prior art it is standard practice to draw in and convey the steam/CS.sub.2 mixture at a temperature of approx. 98.degree. C. using water or another suitable coolant in a parallel-flow configuration. This causes a portion of the steam to condense, while the remaining gas mixture is fed to a carbon disulfide condenser or an activated charcoal absorption system.
The coolant, which simultaneously acts as the means of conveyance, is warmed to temperatures of 50.degree. to 70.degree. C. by the high temperature of the steam/CS.sub.2 mixture. The temperature increase of the coolant depends on the pressure loss in the system, since the volume of coolant to be supplied varies as a function of the pressure loss.
One disadvantage of this process is that the mean is of conveyance is simultaneously the coolant. As a result, a very large quantity of liquid, which is heated by the steam/CS.sub.2 mixture to a temperature which depends on the pressure loss in the system, must subsequently be cooled down to the point of condensation. Cooling such a large quantity of liquid requires a great deal of energy. Another disadvantage of this known process is that relatively large quantities of liquid are required and must be moved.

Process for the recovery of carbon disulfide from a steam/carbon disulfide mixture


A bottling apparatus has a frame and an endless conveyor element on the frame and having a horizontal lower stretch, an upper stretch above the lower stretch, and upstream and downstream corners where the element changes direction. A plurality of pairs of upstream and downstream plates are each secured to the element with the plates of each pair having confronting edges each in turn formed with a cutout. The cutouts of each pair form in the straight stretches a seat adapted to fit snugly around a neck of a bottle. The edges are spaced apart at the corners so that, at the corners, they cannot hold a bottle. A drive advances the element in a horizontal transport direction in the lower stretch and separates the plates of each pair at the upstream and downstream corners. A holder adapted to support at least one bottle at the upstream corner is movable between a loading position fitting the neck of the supported bottle to the cutout of the downstream plate at the upstream corner and a preloading position offset from the upstream corner. Respective spacers hold each of the plates offset from the conveyor element so that as the plates move around the corners they are separated at the edges. These spacers are mounting brackets fixed to the element and to the respective plates.

The present invention relates to an apparatus for filling and handling containers. More particularly this invention concerns such an apparatus for automatically filling bottles in a mass-production operation.
In the production of sterile, filled, and capped bottles it is necessary to move the bottles or other containers through a series of treatment stages. Typically the containers are first sterilized, then subjected to one or two filling stages, then capped. These various actions must take place in a limited time and as closely as possible to each other to maintain sterility, specially when a milk product or something else that is susceptible of spoiling is being charged into the bottles.
U.S. Pat. No. 3,440,794 of Mueller shows a system for making individual-serving cups of milk or cream for restaurant use. It has a conveyor formed with an array of seats that the empty containers are dropped down into. The containers are downwardly tapered so that, when dropped into the seats, they come to rest on their rims. Such a system is not applicable to bottles having a restricted neck, as the body of the bottle is of much larger diameter so that they could not pass through the seats adapted to support them. Thus for such bottles recourse is had to cell-type systems which engage around the bodies of the bottles, so that the positions of the bottle necks and their small openings are not accurately determined. Furthermore the known systems are set up so that they can only work with one size of bottle; adaption to larger or smaller sizes is extremely difficult or impossible.
It is therefore an object of the present invention to provide an improved bottling system.
Another object is the provision of such an improved bottling system which overcomes the above-given disadvantages, that is which allows bottles of different sizes to be easily filled, while exactly positioning the fill openings of the bottles.
A bottling apparatus has according to the invention a frame and an endless conveyor element on the frame and having a horizontal lower stretch, an upper stretch above the lower stretch, and upstream and downstream corners where the element changes direction. A plurality of pairs of upstream and downstream plates are each secured to the element with the plates of each pair having confronting edges each in turn formed with a cutout. The cutouts of each pair form in the straight stretches a seat adapted to fit snugly around a neck of a bottle. The edges are spaced apart at the corners so that, at the corners, they cannot hold a bottle. A drive advances the element in a horizontal transport direction in the lower stretch and separates the plates of each pair at the upstream and downstream corners. A holder adapted to support at least one bottle at the upstream corner is movable between a loading position fitting the neck of the supported bottle to the cutout of the downstream plate at the upstream corner and a preloading position offset from the upstream corner.
With this system, therefore, the bottles are held at their necks. In practice the neck sizes of bottles do not vary much, even when the actual bodies of the bottles can range from fairly small, e.g. 4 oz, to quite large, e.g. 64 oz. Since the bottles hang from the lower stretch, the same apparatus can be used to fill large and small bottles with minor modification.
According to the invention respective spacers hold each of the plates offset from the conveyor element so that as the plates move around the corners they are separated at the edges. These spacers are mounting brackets fixed to the element and to the respective plates.
The cutouts in accordance with the invention are semicircular. In fact the plates of each pair are substantially spectrally identical. In addition each plate is formed with a plurality of the cutouts so that a row of the bottles can be held between each pair of plates.
The holder according to the invention is pivotal about a horizontal axis extending transverse to the transport direction between the loading and preloading positions. Thus the bottle is moved through an arcuate path to fit its neck to the cutout of the downstream plate at the upstream corner, then as the plates move on the upstream plate comes into position to capture the bottle neck. The holder is generally L-shaped and has pockets for as many bottles, normally three or four, that are loaded into the machine at a time.
Each bottle has a body that is substantially bigger than its neck. The seats fit snugly around the neck and form an opening too small for the body to pass through. As a result the bottles are held very solidly so that the filling and capping units downstream can do their jobs without difficulty.
The conveyor element has a upstream and downstream straight end stretches extending vertically between upstream and downstream ends of the upper and lower stretches. Above the lower stretch and below the lower stretch are the units for filling and capping the bottles as they travel from the upstream corner to the downstream corner. Thus the machine is quite compact, with the bodies of the bottles hanging out from the bottom of the machine where they have plenty of room.


A preamplifier stage with dynamically controllable signal gain in a data signal processing circuit that includes a downstream analog-to-digital signal converter. The level of the data signal subsequent to its preamplification is monitored and the gain of the preamplifier stage is dynamically adjusted in response to such data signal transcending one or more predetermined thresholds. Hence, the effective dynamic range of the preamplifier stage is extended, thereby also effectively extending the dynamic range of the overall system beyond that to which it would have otherwise been limited by the dynamic range of the analog-to-digital signal converter. In accordance with a preferred embodiment of the invention, such a preamplifier is used in an X-ray imaging system such as that using flat panel solid state imaging devices.

1. Field of the Invention
The present invention relates to analog amplifiers for preamplifying low-level signals, and in particular, to analog preamplifier circuits having controllable dynamic signal ranges for amplifying charge-biased signals.
2. Description of the Related Art
High dynamic signal range is a key parameter for many types of circuits. This is particularly true in the area of flat panel X-ray imaging systems. As is well known in the art, such systems use a detector cassette containing a scintillation layer that absorbs and converts impinging X-ray photons to visible light photons for detection by photosensitive elements that are also within the detector array. As is further well known, such a detector array contains a two dimensional array of microscopic squares referred to as picture elements, or xe2x80x9cpixelsxe2x80x9d. Each pixel includes an addressable photosensitive element, such as a photodiode and switching transistor combination. From such circuitry individual pixel data signals, generally in the form of charge-based signals, are provided for amplification and further processing. Further discussion of this type of imaging system can be found in commonly assigned U.S. Pat. No. 5,970,115, entitled xe2x80x9cMultiple Mode Digital X-Ray Imaging Systemxe2x80x9d, the disclosure of which is incorporated herein by reference.
As part of the processing of such data signals, following preamplification and some form of a sample and hold operation, such signals are converted to digital signals using an analog-to-digital conversion circuit (ADC). Generally it is this ADC circuitry that sets, or limits, the maximum dynamic range of the system, typically at 14 bits. Such a maximum dynamic range, however, in the field of flat panel X-ray imaging systems has been an impediment to the commercial success of such systems. Accordingly, it would be desirable to have a technique whereby the maximum dynamic range can be extended and thus, be more independent from the maximum range of the ADC circuitry.
In accordance with the presently claimed invention, a dynamically controllable dynamic signal range is provided in the preamplifier stage of a data signal processing circuit that includes a downstream analog-to-digital signal converter. By monitoring the level of the data signal subsequent to its preamplification, the gain of the preamplifier stage is dynamically adjusted, thereby extending the effective, or usable, dynamic range of the preamplifier stage. This provides the further advantage of effectively extending the dynamic range of the overall system beyond that to which it would have otherwise been limited by the dynamic range of the analog-to-digital signal converter. One particularly advantageous application for this invention is in an X-ray imaging system such as that using flat panel solid state imaging devices.
Data signal amplification and processing circuitry with a dynamically controllable dynamic signal range in accordance with one embodiment of the presently claimed invention includes input and output terminals, amplification and processing circuitry, and control circuitry. The input terminal is for conveying an input data signal having a data signal charge associated therewith. The output terminal is for conveying an output data signal corresponding to the input data signal. The amplification and processing circuitry, coupled between the input and output terminals and including preamplification circuitry with a variable feedback capacitance associated therewith, receives a gain control signal and the input data signal and generates the output data signal, wherein a ratio of the output and input data signals is a function of the data signal charge and feedback capacitance and is responsive to the gain control signal. The control circuitry, coupled between the output terminal and the amplification and processing circuitry, monitors the output data signal and controls the variable feedback capacitance via the gain control signal, wherein the variable feedback capacitance is changed when the output data signal transcends a predetermined signal threshold.
An X-ray imaging system in accordance with one embodiment of the presently claimed invention includes an X-ray imaging device, amplification and processing circuitry, and control circuitry. The X-ray imaging device provides a plurality of pixel data signals having respective data signal charges associated therewith. The amplification and processing circuitry, coupled to the X-ray imaging device and including preamplification circuitry with a plurality of variable feedback capacitances associated therewith, receives one or more gain control signals and the plurality of pixel data signals and generates a plurality of output data signals corresponding respectively to the plurality of pixel data signals, wherein respective ratios of respective ones of the pluralities of output and pixel data signals are functions of corresponding respective ones of the data signal charges and feedback capacitances and are responsive to respective ones of the one or more gain control signals. The control circuitry, coupled to the amplification and processing circuitry, monitors the plurality of output data signals and controls the plurality of variable feedback capacitances via the one or more gain control signals, wherein respective ones of the plurality of variable feedback capacitances are selectively changed when one or more of the plurality of output data signals transcend one or more predetermined signal thresholds.

Data signal amplifier with automatically controllable dynamic signal range


A method of determining the temperature of a fuel injector in an internal combustion engine includes the steps of supplying current to the fuel injector on engine startup, measuring the supplied current and voltage to the fuel injector, calculating the resistance of the fuel injector based on the measured current and voltage, and determining the temperature of the fuel injector based on the calculated resistance.

The present invention relates to a control system for metering fuel to an internal combustion engine.
A hot start of an internal combustion engine refers to restarting the engine after prolonged operation of the engine, especially under a load, with a brief interruption of operation following it. In the case of a brief interruption of operation of a hot engine, heat will form bubbles of fuel vapor in the fuel supply system that could cause problems during the next start-up if they were to occur directly in the injection valve. These fuel vapor bubbles prevent the regular metering of fuel. It is therefore customary to have a prolonged injection signal emitted under hot-start conditions so that in the event of a fuel vapor lock, a quantity of fuel sufficient for a safe start is supplied to the combustion process. Alternatively, a signal emitted to initiate the circulation of fuel through the valve, via a return line, will flush out bubbles of fuel vapor to prevent vapor lock.
In order to take measures to avoid problems in the case of a hot start of an internal combustion engine, the control system for fuel metering must recognize when a hot-start situation is present. In previous fuel metering control system for an internal combustion engine, a hot-start situation is assumed when the temperature of the coolant of the internal combustion engine is above a pre-assigned threshold temperature and the difference between the present intake air temperature and a stored temperature exceeds a pre-assigned magnitude. The hot-start situation is considered no longer to exist if the coolant temperature of the internal combustion engine lies below a second threshold temperature or if the internal combustion engine has taken in a predetermined quantity of air.
The disadvantage of these previous fuel metering control systems is that the temperature of the coolant is used as the decisive reference magnitude for recognizing a hot-start situation. An increase in coolant temperature may occur with considerable time delay with respect to the temperature in the combustion chamber and therefore also the injection valve. Thus, it may occur in practice that an internal combustion engine, after a cold start, may immediately be driven under a full load for a short time with a brief interruption of operation. In this case, the immediate environment of the combustion chamber and the injection valve is brought to a high operating temperature while the coolant itself remains relatively cool. During the interruption of operation, fuel vapor bubbles may form in the injection valve and make a restart difficult. This is because a hot-start temperature cannot be recognized based on the temperature of the coolant.
The object of the present invention is to provide a control system or signal processing system for metering fuel to an internal combustion engine in such a way that a hot-start situation can be recognized under all operating conditions of the internal combustion engine using a simple cost-effective method.
The method of the present invention starts with the assumption that the main problem of a hot start is caused by the vapor lock inside the injection valve. The detection of the temperature at the injection valve by temperature sensors, however, would involve a considerable cost because there would have to be room to install such sensors, and a signal line would have to run from the sensor. In addition, it would be necessary to monitor the sensor in order to test the functional capability of the sensor.
The method of the present invention makes use of the fact that the resistance of an electrical conductor changes with temperature. This is also true for the electrical conductors located on the electrical opening device of the injection valve which generally have the form of a magnetic coil. If these conductors are carrying current, then the signal processing system provided for supplying fuel can determine, by known methods, the flow of current as well as the present voltage. Using Ohm""s law, these values enable calculation of the actual present electrical resistance of the conductor. From the present electrical resistance and also using the above-mentioned signal processing system, the present temperature at the location of the electrical conductor can be determined directly on the injection valve. By comparison of the present temperature determined with a pre-assigned calibrated temperature value whose value is determined empirically as the limiting temperature for a hot-start situation, and which is stored in a signal processing system, the hot-start situation can be identified very precisely as a function of the temperature status at the injection valve. The hot-start situation can be identified independent of prior or subsequent states in other locations in the internal combustion engine. Special sensors and signal transmission lines and terminals for their functional control are not required.
By choosing a material for the electrical conductor whose temperature-variable resistance is known, one may influence the response behavior of the control system for recognizing a hot-start situation. The values of the present temperature on the injection valve as a function of voltage and resistance on the electrical conductor of the opening device may be stored in a memory in the signal processing system. Accordingly, the temperature values are available in real time even in the case of very small computational power of the signal processing system.
When the control system of the present invention is used on different internal combustion engines of a model series, varying operating conditions can be allowed for by using additional memory with correction factors. These correction factors can also be stored in a memory for the control system individually during the programming of the computer control system for a specific internal combustion engine, or they can be stored in a fixed memory and called up specifically for a given model series.
The method of the present invention may be executed in any known electronic engine control system or signal processing system.

Control system for metering fuel to an internal combustion engine