High Brightness Electron Beam Diagnostics and their ... - CASA
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High Brightness Electron Beam Diagnostics and their ... - CASA

High Brightness Electron Beam Diagnostics and their ... - CASA High Brightness Electron Beam Diagnostics and their ... - CASA

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5.28Comparisonfor=0:2%(topleft)andfor=2%(topright)ofthebeamrmssize 5.29Schematicsoftheavailablediagnosticsintheundulatorregionformeasuringthe dashedlineontheseplotsisthebeamsizecontributionduetodispersiononly. variationinthecenterofthebunchcompressorversustheexcitationofanupstream quadrupoleusingdimadsimulation(solidlines),usingEqn.(5.57)(crosses).The 5.30ComparisonofthelongitudinalphasespaceattheCTRfoil(greydots)andthe right)............................................135 Thebottomplotspresenttheratioofthebeamsizecontributionduetodispersion decompressormid-point(blackdots).Theenergydistributionareexactlythesame longitudinalemittance....................................135 onlywiththetotalbeamsizefor=0:2%(bottomleft)and=2%(bottom 5.31rmsenergyspreadinducedbywakeeldsgeneratedasa60pCbunchofelectron 6.1SimpliedschematicoftheIRFELphotoinjector(seetextforexplanation)......138 travelsthroughthevacuumchambertransitionattheundulatorlocation.......136 whilethebunchlengthattheCTRfoilissmaller(dashedlines)thanatthechicane mid-point(solidlines)....................................136 6.3\spacechargeoveremittanceratioforthetransverse(Rr)andlongitudinal(Rz) 6.2RMStransverse(xandy)andlongitudinal(z)beamsizesalongtheinjector. Thebottomschematicslocatestheopticalelementsalongthebeamline(thegun acceleratingvoltageis350keV)..............................139 6.5Focallengthoftherst(cavity#4)andsecond(cavity#3)cryounitcavitiesversus 6.4Reducedenergygain,,alongtherst(cavity#4)andsecond(cavity#3)cryounit cavity.............................................142 direction...........................................141 6.7Comparisonofthetransversebeamdensitymeasuredattheexitoftheaccelerating 6.6SteeringeectduetoFPandHOMcouplerinthecryounitversus,thephase structure(A)withparticlepushingnumericalsimulation(B)..............146 dierencew.r.t.themaximumenergyphase(so-called\crestphase").........145 ,thephasedierencew.r.t.themaximumenergyphase(so-called\crestphase")144 6.8Measured(squares)andpredictedtransverseemittances(solidanddashlines)atthe 6.9BeamdensitymeasuredonthehighdispersionOTRmonitorforninedierentbunch cryounitexitversustheemittancesolenoidmagneticeld................147 gradientsettings(theimages(A)to(I)correspondstothepointspresenteding.6.10 startingfromthelowgradientvalues)..........................148

6.10Comparisonofthermstransversehorizontalbeamsizemeasuredinthehighdisper- 6.11\R55"transfermapgeneratedwithparmelafor(1)dierentcavitymodel(3Dmaa 6.12\R55"transfermapfordierentexperimentaloperatingpointsofthebunchergrasionOTRmonitorwiththeoneexpectedfromparmela................149 numericalsimulations.(Firstseriesofmeasurement)..................151 dient.Themeasurementsarealsocomparedwiththe\ideal"injectordevisedfrom thecasewherethepickupcavityislocateddownstreamthecryounitafteradriftin adispersion-freeregion...................................150 and2Dsupersh)atthepickupcavitylocatedintheinjectionchicaneand(2)for 6.13ComparisonofthemeasuredR55patternaftertheFELwasoptimizedwiththe 6.14rmsbunchlengthevolutionalongtheIRFELfromthephotocathodeuptotheexit 6.15Variationofthebunchlengthversusthelinacacceleratingphaseperparmelasim- \ideal"R55patterngeneratedwithparmela(usingthesecondsetup).........152 ofthesecondchicane....................................153 6.16Phasespacedistortionduetochromaticaberrationatthedecompressorchicaneexit (topplots)andthearc1exit(bottomplots).......................156 coveredfromtheCTRautocorrelationusingthetechniquementionedinChapter5]. Comparisonbetweentheexperimentalandsimulatedbunchlongitudinaldistribution (C).TotalCTRpowersignalmeasuredduringplot(B)experiment(D).......154 ulation(A)andmeasured(B)["measured"meansthebunchdistributionwasre 6.17Emittancegrowthduetochromaticaberrationversusthemomentumspreadand 6.19SchematicsofCSRselfinteractionofabunch.......................160 6.18Evolutionofbeamparameters(bunchlengthz,rmsenergyspreadE,transverse emittances~"x;y,andrmsbeamsizesx;y)versustheoperatingacceleratingphaseof thelinac...........................................158 energyosetofthebeam..................................157 6.20AnalyticalcomputationforCSR-inducedenergylossalongagaussianbunchand 6.21TransverseHorizontalemittanceandtotalpowerCTRsignalmeasuredasafunction 6.22Energydistributionmeasuredalongthebeamline,atthechicanemidpoint(A)and chicane(macroparticlewith>0areinthebunchtail)................161 predictionusingasimplenumericalmodelinamodiedversionofthescparmela codefor200m(A)and100m(B).Thesystemconsideredisasimpleachromatic ofthelinacgangphase...................................162 (B)andentranceofthearcs(C)and(D)[thehorizontalaxisoftheseplotrepresent therelativeenergyspread(nounits)].Thebottomplotpresentsthermsrelative energyspreadcomputedfromthedistributions......................163

5.28Comparisonfor=0:2%(topleft)<strong>and</strong>for=2%(topright)ofthebeamrmssize<br />

5.29Schematicsoftheavailablediagnosticsintheundulatorregionformeasuringthe dashedlineontheseplotsisthebeamsizecontributionduetodispersiononly. variationinthecenterofthebunchcompressorversustheexcitationofanupstream quadrupoleusingdimadsimulation(solidlines),usingEqn.(5.57)(crosses).The<br />

5.30ComparisonofthelongitudinalphasespaceattheCTRfoil(greydots)<strong>and</strong>the right)............................................135 Thebottomplotspresenttheratioofthebeamsizecontributionduetodispersion<br />

decompressormid-point(blackdots).Theenergydistributionareexactlythesame longitudinalemittance....................................135 onlywiththetotalbeamsizefor=0:2%(bottomleft)<strong>and</strong>=2%(bottom<br />

5.31rmsenergyspreadinducedbywakeeldsgeneratedasa60pCbunchofelectron 6.1SimpliedschematicoftheIRFELphotoinjector(seetextforexplanation)......138 travelsthroughthevacuumchambertransitionattheundulatorlocation.......136 whilethebunchlengthattheCTRfoilissmaller(dashedlines)thanatthechicane mid-point(solidlines)....................................136<br />

6.3\spacechargeoveremittanceratioforthetransverse(Rr)<strong>and</strong>longitudinal(Rz) 6.2RMStransverse(x<strong>and</strong>y)<strong>and</strong>longitudinal(z)beamsizesalongtheinjector. Thebottomschematicslocatestheopticalelementsalongthebeamline(thegun acceleratingvoltageis350keV)..............................139<br />

6.5Focallengthoftherst(cavity#4)<strong>and</strong>second(cavity#3)cryounitcavitiesversus 6.4Reducedenergygain,,alongtherst(cavity#4)<strong>and</strong>second(cavity#3)cryounit cavity.............................................142 direction...........................................141<br />

6.7Comparisonofthetransversebeamdensitymeasuredattheexitoftheaccelerating 6.6SteeringeectduetoFP<strong>and</strong>HOMcouplerinthecryounitversus,thephase structure(A)withparticlepushingnumericalsimulation(B)..............146 dierencew.r.t.themaximumenergyphase(so-called\crestphase").........145 ,thephasedierencew.r.t.themaximumenergyphase(so-called\crestphase")144<br />

6.8Measured(squares)<strong>and</strong>predictedtransverseemittances(solid<strong>and</strong>dashlines)atthe 6.9<strong>Beam</strong>densitymeasuredonthehighdispersionOTRmonitorforninedierentbunch cryounitexitversustheemittancesolenoidmagneticeld................147 gradientsettings(theimages(A)to(I)correspondstothepointspresenteding.6.10 startingfromthelowgradientvalues)..........................148

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