High Brightness Electron Beam Diagnostics and their ... - CASA
High Brightness Electron Beam Diagnostics and their ... - CASA High Brightness Electron Beam Diagnostics and their ... - CASA
4.3MaximumaveragecurrentthatcanwithstandaTRradiatorasafunctionofthe 4.2MethodologytocomputetemperatureriseinacylindricallysymmetricTRradiator.55 4.4SteadystatetemperatureversusaveragebeamcurrentforthreedierentTRradiator equivalentbeamradius.ThreetypesofTRradiatorhavebeenconsidered:Aluminum,GoldandCarbon.Thethreeradiatorare0:8mthick.............574.6Angularscatteringdistributionexperimentallymeasuredforthreedierentthick- 4.5Anexampleoftheeectofa0:8mthickaluminumfoilonthebeamprole.The nessesofAluminumfoil...................................60 beamismeasuredusingawirescannerlocateddownstreamthefoil..........59 thicknessandabeamequivalentradiusof2mm.....................58 4.9OverviewofthecarbonfoilbasedOTRexperiment(CourtesyfromS.Spata)(A) 4.7ComparativeresultsofexperimentwithKeil'ssemi-empiricaltheoryandgeant 4.10ComparisonoftheMissingmassspectraobtainedusingoneoftheexperimentalhall 4.8geantcomputationforthincarbonfoils.........................63 andatypicalbeamdensitymeasuredwithsuchdevice(B)...............64 computationforthinaluminumfoils............................62 spectrometerwith(A)andwithout(B)thebeambeinginterceptedbythecarbon 4.13Comparisonofbeamspotsizevariationversusquadrupolestrengthfortwodierent 4.11StandardcongurationoftheOTR-basedprolemonitorintheFEL-driveraccelerator.66 4.12Rawdatabeamprole(topgraph)andbeamproleafterprocessing(background foil(CourtesyofP.Gueye,HamptonUniversity,VAUSA)...............65 4.14Relativeerroroncomputedemittanceforthetwocasespresentedingure4.13 versustherelativeerroronbeamsizemeasurement...................76 and6m............................................75 settingoftheupstreamopticstoachievetwodierentminimumbetatronvalue,3 subtracted,ghostpulsecontributionremoved,...).....................67 4.16Relativeemittanceerrorversusdimensionlessspuriousdispersioncontributionto 4.15Monte-Carlosimulationof200emittancemeasurements.Theplots(fromtop)are theun-normalizedrmsemittance,the-function,theparameter...........77 beamsize..........................................78
4.18Overviewofthephasespacesamplingtechnique.AnincomingAmultislitmask 4.17AnexampleoftransverseemittancemeasurementinthehighenergyregionoftheIRinterceptstheincomingspace-charge-dominatedbeam.Thebeamletsissuedfrom numberarethebeamparametersdeducedfromthet.Thechargeperbunchwas Thedashedlinesareobtainedwiththeleastsquarettechnique.Thereported approximatelysetto40pC.................................79 (top)andvertical(bottom)rmsbeamsizeversustheexcitationofthequadrupole. FELusingquadrupolescanmethod.Thetwoplotspresentvariationofthehorizontal 4.20Comparisonoftheexpectedphase-space,generatedviaparticleretracing(eachgrey 4.19Simulatedmulti-beamletspatternontheopticaltransitionradiationradiator....84 dotsrepresentamacroparticle),withtheretrievedphase-space(representedwith backlineiso-contours)usingthesimulatedbeampatternontheopticaltransition radiationpresentedgure4.19..............................85 theslitsareemittance-dominated.............................80 4.21Fractionofincidentelectronthatscattersontheslitsedgeversusthebeamincident 4.23Anexampleofreconstructedphasespaceiso-contourdensity..............90 4.22Anexampleof2Dbeamdistributionontheanalyzerscreendownstreamthemultislit mask.Theprojectionontothex-axisisalsodisplayed..................89 anglewithrespecttothenormalaxisofthemultislitmask.Thedepthoftheslits approximatelytheinteractionof10%oftheincidentelectronwiththematerial....86 is5mm.Amisalignmentofthemaskof1:2mradcomparetothebeamaxisyields 4.24Emittanceandbetatronfunctionversusthesolenoidexcitation.............91 5.1SequencesofparmelarunsdemonstratingthebunchingprocessintheIRFEL. 4.25Emittanceasafunctionofthechargeperbunchfortwodierentmacropulsewidth (10secand50sec)....................................92 5.2AngularBFFforthreedierentvalueoftheRMSbeamdivergence..........97 (H),thearc#1(I).Notethatelectronswithpositivebelongtothebunchtail SRF-linac(F),thebunchcompressorchicane(G),thebunchdecompressorchicane whiletheonewithnegativeareinthebunchhead..................95 theSRF-cavity#1(C),theSRF-cavity#2(D),theachromaticchicane(E),the Thelongitudinalphasespaceisplottedattheexitofthegun(A),thebuncher(B), 5.3Bunchformfactorcomputedfora300m(RMS)square(dashline)andgaussian 5.4Monte-Carlosimulatedbunchformfactor(right)with106macroparticleforthree (solidline)bunches.....................................98 typesofbunchlongitudinaldistribution(left)......................99
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4.18Overviewofthephasespacesamplingtechnique.AnincomingAmultislitmask 4.17AnexampleoftransverseemittancemeasurementinthehighenergyregionoftheIRinterceptstheincomingspace-charge-dominatedbeam.Thebeamletsissuedfrom<br />
numberarethebeamparametersdeducedfromthet.Thechargeperbunchwas Thedashedlinesareobtainedwiththeleastsquarettechnique.Thereported approximatelysetto40pC.................................79 (top)<strong>and</strong>vertical(bottom)rmsbeamsizeversustheexcitationofthequadrupole. FELusingquadrupolescanmethod.Thetwoplotspresentvariationofthehorizontal<br />
4.20Comparisonoftheexpectedphase-space,generatedviaparticleretracing(eachgrey 4.19Simulatedmulti-beamletspatternontheopticaltransitionradiationradiator....84 dotsrepresentamacroparticle),withtheretrievedphase-space(representedwith backlineiso-contours)usingthesimulatedbeampatternontheopticaltransition radiationpresentedgure4.19..............................85 theslitsareemittance-dominated.............................80<br />
4.21Fractionofincidentelectronthatscattersontheslitsedgeversusthebeamincident<br />
4.23Anexampleofreconstructedphasespaceiso-contourdensity..............90 4.22Anexampleof2Dbeamdistributionontheanalyzerscreendownstreamthemultislit mask.Theprojectionontothex-axisisalsodisplayed..................89 anglewithrespecttothenormalaxisofthemultislitmask.Thedepthoftheslits approximatelytheinteractionof10%oftheincidentelectronwiththematerial....86 is5mm.Amisalignmentofthemaskof1:2mradcomparetothebeamaxisyields<br />
4.24Emittance<strong>and</strong>betatronfunctionversusthesolenoidexcitation.............91 5.1SequencesofparmelarunsdemonstratingthebunchingprocessintheIRFEL. 4.25Emittanceasafunctionofthechargeperbunchfortwodierentmacropulsewidth (10sec<strong>and</strong>50sec)....................................92<br />
5.2AngularBFFforthreedierentvalueoftheRMSbeamdivergence..........97 (H),thearc#1(I).Notethatelectronswithpositivebelongtothebunchtail SRF-linac(F),thebunchcompressorchicane(G),thebunchdecompressorchicane whiletheonewithnegativeareinthebunchhead..................95 theSRF-cavity#1(C),theSRF-cavity#2(D),theachromaticchicane(E),the Thelongitudinalphasespaceisplottedattheexitofthegun(A),thebuncher(B),<br />
5.3Bunchformfactorcomputedfora300m(RMS)square(dashline)<strong>and</strong>gaussian 5.4Monte-Carlosimulatedbunchformfactor(right)with106macroparticleforthree (solidline)bunches.....................................98 typesofbunchlongitudinaldistribution(left)......................99