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

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4 2 0 R55patterngeneratedwithparmela(usingthesecondsetup). (positioni)toitsexit(positionf): Figure6.13:ComparisonofthemeasuredR55patternaftertheFELwasoptimizedwiththe\ideal" −2 Measurement Simulation −4 whichindeedessentiallymodifythecorrelationtermhzii.Hence,undertheassumptionthatthe −6 bunchisnotsignicantlyvaryingwiththelinacsetpoint,theminimumbunchlengthisgivenby wherewehaveusedthedenitionofrmslongitudinalemittancetowritethefarrightexpression. Inthepresentconguration,theparameterattheentranceofthechicanearesetbythelinac; hz2if=R255hz2ii+2R55R56hzii+R256h2ii=R255hz2ii+2R55R56hzii+R256~"2z+hzi2i hz2ii(6.16) −40 −20 0 20 40 Drive−Laser Phase φIN (RF−Deg) caneispresentedingure6.14.Experimentallythetypicalbunchlengthmeasuredintheundulatorcomputedaccordingtoparmelafromthephotocathodesurfaceuptotheexitofthesecondchiditionforachievingminimalbunchlengthafterthecompressorsystemis(dE=dz)i=1=R56.By settingthelinacphaseandacceleratinggradientsuchthattheaforementionedmatchingcondition isfullled,andbecauseoftheinitialemittance,theminimumbunchlengthachieved,vianumerical simulations,attheundulatorlocationisabout140m(rms).Theevolutionofthebunchlength introducethelongitudinalphasespaceslope(dE=dz)i=hzii=hz2ii;thereforethe\matching"con- thecondition@hz2if=@hzii=0,whichgivestherelationhzii=hz2ii=1=R56;bydenitionwe vicinityisapproximately100m(rms),anexampleofreconstructedbunchshape(usingtheinverse HilberttransformtechniquedetailedinChapter5)iscomparedwithabeamprolegeneratedwith parmelaingure6.15(C).Withinthelevelofaccuracy7,wehavegoodagreement.Byvaryingthe phaseofthelinac(therebychangingthequantityhzii)wecanvarythebunchlength;wepresent theresultofsuchanexperimentingure6.15(B)alongwithresultsfromnumericalsimulation(in donotgiveauniquelongitudinaldistribution,andtherearealotofassumptionsthathavetobeconsidered(e.g. extrapolationoftheCTRspectrumatlowfrequency,...) 7(1)weonlyused500macroparticlesinthenumericalsimulation,(2)theHilberttransformation,aswehaveseen T−O−F at Pickup Cavity φ OUT (RF−deg)
10 1 5 10 0 500 1000 1500 2000 2500 3000 3500 4000 Distance from photocathode (cm) -1 10 5 2 0 2 thesecondchicane. Figure6.14:rmsbunchlengthevolutionalongtheIRFELfromthephotocathodeuptotheexitof Injector Chicane Chicane plot(B));forcompletenesswealsoincludeingure6.15(D)thetotalCTRpowerdetected.Wend Aswementionedintheverybeginningofthisreport,onemotivation,foroperationalpurpose,of tothemeasuredvariation. 6.3BeamParametersMeasurementPriorto\Firstlasing" thatthebunchlengthpredictedvianumericalmodelinghasalesspronouncedvariationcompared sucientbeamqualitytoenabletheFELtooperatehowevertheachievedparametersaresomewhat largerthantheonethatcouldbetheoreticallyreachedaspredictedfromnumericalmodeling,except theexperimentallyachievedandthenumericallyexpectedvalues.Itisseenthatwehaveachieved damagedtheundulatorbecauseofradiationshowersinducedastheelectronbeam"scrapes"on thevacuumchamber.Intable6.3wepresentsomeofthebeamparametersrequiredalongwith magnetwasremoved,themainreasonbeingthatduringthis\tuningperiod"wecouldhave thediagnosticsdevelopedhereinistoverifytheelectronbeamqualityiswithinthespecications forthebunchlength.Withtheaboveparametersrstlightwasachievedatlowdutycyclewithina toenabletheFELtolase.IntheearlystageofthecommissioningoftheIRFEL,theundulator betweenthenumericalmodelandtheachievedparameter. beam.OntheBeamPhysicspointofviewitisinterestingtotrytounderstandthediscrepancies coupleofhoursafterweinstalledtheundulatormagnet,andtwodayslaterwewereabletooperate theFELwithanoutputpowerof150W(cw),therebydemonstratingthequalityoftheelectron RMS bunch length (mm) Wiggler Location
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HighBrightnessElectronBeamDiagnosti
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eratedupto48MeVpriortothelasingsyst
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IthanktheCEBAFmachineoperators,with
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3.4MeasurementoftheLongitudinalResp
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5.6ZerophasingTechniqueforBunchLeng
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ListofTables 3.2Comparisonofcoecien
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ListofFigures 1.1Comparisonoftheexp
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3.11Momentumcompactionandnonlinearm
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4.18Overviewofthephasespacesampling
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5.16Interferogrammeasuredfordierent
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6.10Comparisonofthermstransversehor
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Chapter1 UVdomainandareplannedtogen
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space-chargeinthelowenergyregime,an
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!Vjitsthevelocity,and!Xjisthepositi
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equation boundarybetweenvacuumandam
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10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.
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1.0 0.8 0.6 0.4 0.2 E=10 MeV E=42 M
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00000000000000000000000000000000000
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harmonicwithproperchoiceoftheKvalue
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Bu(rms)0.28T ParameterValueUnit Nu
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2.7TheJeersonLabIRproject usedasexp
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Study TheFELdriveraccelerator:Latti
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ParameterValue x -0.178 x(m) 8.331
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Thepurposeofmeasuringthetransverser
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computedusingthelatticeset-upuseddu
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etatronexcitationaspicturedingure3.
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∆ x (mm), Corrector 0F00H ∆ x (
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1 0.5 0 spreadoftheparticlewassetto
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2 1 −5 −3 −1 1 3 5 k (m q −
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Experimentallythecalibrationcoecien
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tioned.FromthetransferfunctioninFig
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Pickup Experiment #2 #3 #4 Simulati
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Fromthesebothmeasurementitispossibl
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. . . . . . . . . . . . . . . . . .
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10 5 Sext. ON Figure3.20:Eectofthes
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spaceabeamthatconsistsofNparticles,
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Asforthegeometricemittanceonecanden
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(a) ceramic radiator beam x-wire be
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and validundertheassumptionofaunifo
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1000 900 800 700 Figure4.4:Steadyst
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Fraction of Beam enclosed within (%
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5 2 2 3 4 5 6 7 8 9 10 0 10 5 2 Foi
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Actuator Inserts Foil and Mirror CI
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shortterm,touseasbeamdensitymonitor
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Alongwiththeseimplementedoperations
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whereiistheerrorontheithbeamsizemea
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Let'sassumethethinlensapproximation
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obtainedviathestatisticalanalysis.T
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20 18 16 . 14 . 12 . Figure4.14:Rel
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100 10 −3 10 −2 10 −1 10 that
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multislits mask (copper) Aluminum F
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TheReductionoftheSpaceChargeconditi
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. . . . . . . . . . . . . . . . . .
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Table4.7:Typicalsystematicerroronem
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180 8 160 6 Figure4.22:Anexampleof2
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4.0 3.5 3.0 2.5 Figure4.24:Emittanc
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Characterization LongitudinalPhaseS
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concentrateonthebeamparametersinthe
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1.1 1 mrad 0.9 5 mrad mainlyduetoth
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Population Population 100000 90000
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Page 133 and 134: FinallyitisinterestingtonotethatFou
Page 135 and 136: Itsautocorrelationis:S(z)=8>:(1=w2)
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Page 159 and 160: BeamDynamicsStudies Chapter6 undula
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Page 169 and 170: ε x (mm−mrad) Nominal 6 4 2 cryo
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Page 187 and 188: Conclusion Chapter7 Therecirculator
Page 189 and 190: [2]Y.Shibata,T.Takahashi,T.Kanai,K.
Page 191 and 192: [29]J.-C.Denard,C.Bochetta,G.Traomb
Page 193 and 194: [65]B.C.Yunn,\ImpedancesintheIRFEL"
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Page 201 and 202: Initialization MAIN Stop INPUT DECK
Page 203 and 204: C.0.6TheDispersionRelationsfor^S(!)
Page 205 and 206: have: Howeveritshouldbenotedthatweh
Page 207: FigureD.1:OverviewoftheRF-controlsy
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