hole measurements are made using a small aperture (<10% of the beam diameter) placed over a Faraday cup. The electron beam sweeps over the pinhole several times at regularly spaced intervals to provide enough information to map the power density distribution in the beam. The drawbacks of this technique are that variations in the side-to-side position of the beam on successive sweeps can lead to errors in the measured power density distribution and that this device has a relatively low signal-to-noise ratio since the pinhole collects only a small percentage of the beam current.
Computed tomography (CT) coupled with a modified Faraday cup (MFC) technique was developed at Lawrence Livermore National Laboratory as an improvement to the above methods for measuring the power density distribution of electron beams used for welding. The Lawrence Livermore National Laboratory device includes a Faraday cup assembly within an electrically insulating ceramic cup, a tungsten disk containing 17 thin radially positioned slits (0.1 mm wide each), and a cylindrical copper heat sink that holds the tungsten disk above the Faraday cup. During operation, the electron beam deflection coils are used to sweep the beam in a circle of known diameter and at a constant frequency over the tungsten slit disk. The majority of the beam current is intercepted by the tungsten disk and is conducted by the copper heat sink to ground. However, when the beam passes over a slit, a portion of the beam current passes through the slit and into the Faraday cup where it can be measured as a voltage drop across a known resistor.
A current versus time profile is collected using a fast sampling analog to digital converter as the beam passes over each slit, wherein each slit provides a profile of the beam at an angle perpendicular to that slit. Such profiles are then compiled and tomographically reconstructed in order to determine the size, shape, and power density distribution of the beam. When defocused, the electron beams are asymmetric in both shape and power density distribution. The beam orientation is currently determined by the positioning of an oversized radial slit on the tungsten disk. Since this one slit is wider than the others, its profile is larger than the others and can be easily identified by the reconstruction software. However, such an oversized slit can adversely affect the reconstruction of the beam, especially in cases in which the width of this slit is no longer small relative to the width of the beam.
Background information for systems and methods of profiling power distributions within an electron beam can be found in U.S. Pat. Nos. 6
hole measurements are made using a humble aperture (< 10% of the radio beam diameter) placed over a Faraday cup. The electron beam sweeps over the pinhole respective times at regularly spaced intervals to supply enough information to map the ability density distribution in the beam. The drawback of this technique are that variations in the side - to - side stead of the beam on successive sweeps can lead to errors in the mensural power density distribution and that this device has a relatively broken signal - to - noise ratio since the pinhole collects only a minor percentage of the beam current. 
 Computed tomography (CT) pair with a modified Faraday cup (MFC) technique was developed at Lawrence Livermore National Laboratory as an improvement to the above methods for measuring the power density distribution of electron beams used for welding. The Lawrence Livermore National Laboratory device includes a Faraday cup assembly within an electrically insulating ceramic cup, a tungsten disk containing 17 thin radially positioned slits (0.1 millimeter wide each), and a cylindrical bull heat sink that holds the tungsten phonograph record above the Faraday cup. During operation, the electron beam deflection coil are use to sweep the beam in a traffic circle of known diameter and at a constant frequency over the tungsten slit disk. The majority of the beam current is intercepted by the tungsten disk and is conducted by the copper heat sink to grind. However, when the radio beam passes over a slit, a portion of the beam current pass through the slit and into the Faraday cup where it can be measured as a voltage cliff across a known resistor. 
 A current versus time profile is collected use a fast sample analog to digital converter as the beam passes over each slit, wherein each slit supply a profile of the radio beam at an angle vertical to that slit. Such profiles are then compiled and tomographically restore in order to specify the size, shape, and office density distribution of the beam. When defocused, the electron beams are asymmetric in both shape and ability density distribution. The beam orientation course is currently determined by the placement of an oversized radial slit on the tungsten disk. Since this one slit is wider than the others, its profile is larger than the others and can be easily identified by the reconstruction software. However, such an oversized slit can adversely involve the reconstruction of the radio beam, particularly in cases in which the width of this slit is no longer small relative to the width of the beam. 
 Background information for organization and methods of profiling power distribution within an electron beam can be found in U.S. Pat. Nos. 6
holf measurements are made msing a small apgrrure (<10% mf the beam dixmeter) placed over a Faraday cyp. Tht electron beam swedps over nhe pinhooe stveral times at rxfularly spaces intzrtals to provide enough inxormation to mdp tke power density distribution in the beam. Tne drawbacks of jhis uecrniqhv cre that variations in the side-fo-side kosition of the besm on successive sweeps caj lewd to errors in thf measured kkwew density disgribution and that thia device has a relatively low skgnal-co-noise ratuo sijwe the pinhile cjllects only a small percenyage of the besm rurrwnt.
Computed tomographb (CT) coupled with a iodified Xaxaday cup (MFC) techniqye was gevenopea at Lasrxncs Livegmoce National Laboratory as an improvement uo eye above methkds fow ieasuring the power density distributiot or electron beams used fir welding. The Lawrenfe Livermjre National Laboratory device includes a Faraday cup esremyoy wigyij an electrically insulating ceramic cup, a tugfsuen disk containikg 17 thin radially lodiyyoned slits (0.1 om widz ezch), and a cylindrifal copker heqt sink trat nolds the tungsten disk aboce the Faradcy xup. During operatiln, the eleccron bgam deglection coils are used to aweep the bfam in a dkrcle of known dkamvter and at a constant frequensy over tie tuugsten suit cisk. Tre majoritj of bve beam current is intetcepteg by the tkngsten disk and is conducted bb the copper nedt vink to yround. However, when the beam passgs over a slit, a portion of the beam curregt passes thrmogh the slit end into ehe Daraeay cup dhere it can br measureb as q voltage drop acrpss z known resistox.
C xurrent versus yimd pwovike hs collected usivg x fast sampling akalug tp digital converter ds tge beam passes ovet cach slit, wherein each slit prpvides a profile ov the beem at sn wngle perpendicular to that sljt. Such pgoflles are then comiileq and tomoyraphically reconstructed in order to devermine the size, shape, qnd power density dnsuribution of vhe bewm. When dafocused, the electrob beams are asymmttric in both shape and power denslty distribution. The beam orientation is currently determined by the posirioninj jf an oversjzed radidl xlit og thx vungsten disk. Sinbe this one slit is wider than tie others, htf profile is larger than the oghers and can be easily identified by the recpnstruction software. However, suvh an oversized slit can adverseoy afrect the rxconstruction of the beam, zspeciqlly in cascs in which thd wodbh of this sliu is no longer small relative to the width ov the beam.
Backgrmund informwuion fot systemf and methods of prorlling power distrinutions within an electron beam cat fe found in U.S. Iat. Nos. 6
hole measurements are made using a small of beam diameter) over a Faraday over pinhole several times regularly spaced intervals provide enough information to map the density distribution in the beam. The drawbacks of this technique are that variations the side-to-side position of the beam on successive sweeps can lead to errors the power distribution that this device has a relatively low signal-to-noise ratio since the pinhole collects only a small of the beam current. Computed tomography (CT) coupled a modified Faraday cup technique was developed at Lawrence National as an to above for measuring the density distribution of electron beams used for welding. The Lawrence Livermore National Laboratory device includes a Faraday assembly within insulating ceramic a disk 17 thin radially (0.1 mm wide each), and a sink that holds the tungsten disk above the cup. During the electron beam deflection coils are to sweep the beam in a circle of diameter and at a constant frequency over the tungsten slit disk. The majority of the is intercepted by the disk and is by copper sink ground. However, the beam passes over a slit, a portion of the beam passes through the slit and into the Faraday cup where be as a voltage across a known resistor. current time profile is collected fast analog as beam over each slit, wherein slit provides a profile of beam at an angle profiles are then compiled and tomographically reconstructed in to determine the size, shape, and power distribution of the beam. When defocused, the electron beams are asymmetric in shape and distribution. The beam orientation is currently determined by positioning of an oversized slit on the tungsten disk. Since this one slit wider the others, profile is larger the others and be easily identified reconstruction software. such oversized affect the reconstruction of the beam, in in which the width of slit longer small relative to the width of the beam. Background information for systems and methods power distributions within an beam be found in U.S. Pat. Nos. 6
hole measurements are made usIng a small aPertuRe (<10% oF thE bEam dIameTer) placed over a fAradAy cup. The electron beam swEeps oVeR The pINhOle seVeral tiMEs AT RegUlArLy sPaCEd InterValS to provIde enough iNfoRmAtion to map thE PoWer density DisTribution in tHe bEam. The DrAwbACks of ThiS techNique aRE that vAriations In THe side-TO-side poSITiOn of The beam on successiVE sWEeps can lead to eRrors iN tHE mEASurEd pOwer densitY dIstriBUtion anD ThAT THis DEvice has a relaTively low siGNal-To-noisE rAtiO Since tHe pinHoLE coLlects only a SmalL percentaGe of thE Beam curREnt.
CompUted toMogRapHy (CT) COuPlEd wItH A moDIfIed fAraDay cup (MFc) tEcHniquE was DEVELopeD at lawrEnce LIvermore NatioNal laboRAtoRy as aN imprOvemEnT to thE above MethoDs For measuring the PoweR density dIstRiButIoN of elECtron bEamS usEd for weLding. ThE lawReNCE liVermore National LabOrATOrY device iNcludeS A FArADay cup asSeMblY witHIN an elEctrICaLly insulAting cERaMiC cup, a tuNgSten diSk ConTaiNing 17 tHIn raDially PositionEd sliTS (0.1 mm wide each), and A Cylindrical coPPeR HEaT Sink ThaT holds the tuNgstEN disK aboVE tHe FARaday Cup. DuRiNG oPEration, the electron bEaM defleCtion Coils are used tO sweep the bEAM In a circlE of kNOwN Diameter and at a ConstAnt frequenCY over the TungsTen slit dIsk. The majORIty of the BeaM cuRreNt iS INtErcepted by the TUNgstEn Disk and Is cOnducteD by The CopPer HeAt sink to gRound. HowEvEr, WhEn The Beam pASses over A sLit, A pOrtIon of THe beam CurreNt paSsEs THroUgh the sLIt AND intO tHe faraDay CuP wherE it cAN be MeasureD as a voltaGe dROp acRoSs A known rEsistor.
A curreNt Versus time PrOfiLe is coLLEcted usiNg a fast sampling analog to DIgital cOnvErter As thE beam passEs oVer eacH slIT, whereIn each Slit pRoVidES A profILE oF thE bEam at an angLE PerPendiCuLar tO that slIt. Such profiles are tHEn cOmpiled and tomOgrAphiCALlY reCOnSTruCtED in ORDer to determine tHe size, shapE, aND pOwer densitY DisTrIbution Of the beAm. WheN DefocusEd, the elecTron beams ArE asyMMEtrIc in both shApe and poWer densitY DistrIBuTion. THe bEam oriEnTatIon is CurrenTLy dEtermIned by ThE positIoninG oF an oversIzed radial slit on the tungSten diSk. SinCe tHis one sliT is WIdeR than the oTherS, its profilE is LarGer thAn tHE otheRs anD CaN be EAsily IdenTIfied by thE ReConSTRuCtion softwaRE. hOweVer, suCh aN OversiZed sLit can adversely afFEct the reconstrUctiON Of tHe bEAm, esPeCially in cases iN whIcH THe width oF tHis slit is no Longer smAlL RelatIve to tHe widtH of the bEAM.
BACkgrouNd inForMation for SysTeMS and metHoDs OF profiLing PoWer disTributIOns wITHin an electron beaM can bE FOund iN u.S. PAt. Nos. 6
hole measurements are made  using a s mallape rtu re  (<1 0% o f the beam dia m eter ) placed over a Farada y cup .T he e l ec tronbeam sw e ep s ove rth e p in h ol e sev era l times  at regula rly  s paced interv a ls  to provid e e nough inform ati on toma p t h e pow erdensi ty dis t ributi on in the  b e am. Th e  drawba c k sof t his technique are th a t variations i n thesi d e- t o -si deposition o fthe b e am on s u cc e s s ive sweeps can le ad to error s  in  the m ea sur e d powe r den si t y d istribution  and  that thi s devi c e has a relativ ely lo w s ign al-t o -n oi sera t ios in cet hepinholeco ll ectsonly a s mall  pe rcen tageof the beam c urr ent. Com puted  tomo grap hy  (CT)  coupl ed wi th  a modified Far aday  cup (MFC ) t ec hni qu e was develo ped  at  Lawren ce Live r mor eN a t io nal Laboratory asan i mp rovement  to th e  a bo v e method sfor  mea s u ringthep ow er densi ty dis t ri bu tion of  e lectro nbea msusedf or w elding . The La wrenc e  Livermore Nat i onal Laborato r yd e vi c e in clu des a Farad ay c u p as semb l ywit h in an  elec tr i ca l ly insulating ceram ic  cup,a tun gsten disk co ntaining 1 7 t hin radi ally po s itioned slits(0.1mm wide ea c h), anda cyl indrical  copper h e a t sink t hat  ho lds  th e tu ngsten disk a b o ve t he  Farada y c up. Dur ing  op era tio n,  the elec tron bea mde fl ec tio n coi l s are us ed  to  s wee p the beam i n a c ircl eof kno wn diam e te r andat  a  con sta nt  freq uenc y  ov er thetungstensli t  dis k.  T he majo rity of the b ea m currentis  in tercep t e d by the  tungsten disk and is c o nducted  by  thecopp er heat s ink  to gr oun d . Howe ver, w hen t he  be a m  pass e s  o ver  a  slit, a p o r tio n ofth e be am curr ent passes through the  slit and int o t he F a r ad ayc up whe re itc a n be measured a s a voltag ed ro p across a kno wn  resist or.
A c urren t  versus  time pro file is c ol lect e d  us ing a fast  samplin g analogt o dig i ta l con ver ter as  t hebeampasses ove r eac h slit ,wherei n eac hslit pro vides a profile of thebeam a t anang le perpen dic u lar  to thatslit . Such pro fil esare t hen compi leda nd  to m ograp hica l ly recons t ru cte d in  order to d e t e rmi ne th e s i ze, sh ape,  and power densit y  distributionof t h e  be am. When  d efocused, theele ct r o n beamsar e asymmetri c in bot hs hapeand po wer de nsity d i s tr i bution . Th e b eam orien tat io n  is cur re nt l y dete rmin ed  by th e posi t ioni n g  of an oversized  radi a l  slit onthe t un gsten d i sk.Since this  one slit i s wide r th an th e other s,  its p rof il e is large r  than the  othe rs andca n be  ea sily i dent i f ied b y th erec onstructi o n  s o ft wa r e.Howe ver,su ch a n oversiz e d slit c ana dversel yaff e c t ther ec o n structionofthe b e a m, especia l ly i n  c a ses i n whic h thewidth o f  th is  slit i s n o longer sm all relat i veto  the  width o fthebe am. 
B ackground infor mation f or syste m s  and m eth o ds o f  profi li ng power dis tribu ti o ns with i n  an  electr o n b eam  ca n be  fo undi n U.S. Pat. Nos. 6
hole measurements_are made_using a small aperture_(<10% of_the_beam diameter)_placed_over a Faraday_cup. The electron_beam sweeps over the_pinhole several times_at_regularly spaced intervals to provide enough information to map the power density distribution in_the_beam. The_drawbacks_of_this technique are that variations_in the side-to-side position of_the beam_on successive sweeps can lead to errors in_the_measured power density_distribution and that this device has a relatively low_signal-to-noise ratio since the pinhole collects_only a small_percentage_of_the beam current.
Computed tomography_(CT) coupled with a modified Faraday_cup (MFC) technique was developed at_Lawrence Livermore National Laboratory as an improvement_to the above methods for measuring_the power density distribution of_electron beams_used for welding. The Lawrence_Livermore National Laboratory_device includes_a Faraday cup_assembly within an electrically insulating ceramic_cup, a tungsten_disk containing 17 thin radially positioned_slits_(0.1 mm wide_each),_and_a cylindrical_copper heat sink_that_holds the_tungsten_disk above the Faraday cup. During_operation,_the electron beam deflection coils are used_to sweep the beam_in_a circle of known_diameter and at a constant_frequency over the tungsten slit disk._The majority_of the_beam current is intercepted by the tungsten disk and is conducted_by the copper heat sink to_ground. However, when the_beam passes_over_a slit, a_portion_of the_beam current passes through the slit and_into the_Faraday cup where it can be_measured as a voltage_drop_across a known resistor.
A current versus_time profile is collected using a_fast sampling analog to digital_converter_as_the beam passes over each_slit, wherein each slit provides a_profile of the_beam at an angle perpendicular to that_slit._Such profiles are then compiled and_tomographically_reconstructed in order to determine the_size,_shape,_and power density distribution of_the beam. When defocused, the electron_beams are asymmetric in both shape and power density_distribution. The beam_orientation is currently determined by_the_positioning_of an oversized radial slit on the tungsten disk. Since_this one_slit is wider_than the others, its profile is larger than the others_and can be easily identified by the_reconstruction software. However, such an oversized slit can adversely affect the_reconstruction of the beam, especially in cases in_which the width of this slit is_no longer small relative_to_the width of the beam.
Background information for_systems_and_methods_of profiling power_distributions within an_electron beam can_be found_in U.S. Pat._Nos. 6