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

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Reflection and Transmission Coefficents 10 0 10 0 2 5 10 1 2 5 10 2 2 5 10 3 2 5 10 4 Wavenumber (cm -1 10 ) -2 10 5 2 -1 5 R[E ||] wg 2 R[Ek]wgisthereectioncoecientofthewiregridfortheelectriceldcomponentparalleltothe T[E] gc TheenergyspectrumcanbederivedbyFouriertransformingtheautocorrelationdeducedfromthe wires,andT[E]gcisthetransmissioncoecientoftheGolaycellentrancewindow. wires,R[E?]wgisthereectioncoecientofthewiregridforthecomponentperpendiculartothe Figure5.13:LimitationofsomeopticalcomponentsintheMichelsonpolarizinginterferometer. R[E ] wg data.SincetheFouriertransformofasampledfunctionwithsamplingintervaltisa1=t-periodic FastFourierTransformalgorithm(FFT)[47]becauseofthesamplednatureoftheexperimental interferogram.However,wecannotperformanexactFouriertransformandhavetousestandard function,thefrequencyresolutionwillbeoftheorderof1=(2Nt)ifNisthenumberofsamplings 5.5.5ExperimentalResultsUsinganAutocorrelationTechnique acquired.Againnotethatt==cisrelatedtotheOPDandtherefore,foraninterferogram acquiredwithmirrorstepsof,thefrequencyspectrumresolutionis1=(4N). ArstsetofmeasurementswasperformedintheperiodpriorrstlasingoftheIRFEL.Typically,it wasfoundthattheGolaycellcouldeasilydetect,withafairlygoodsignalovernoise,thecoherent transitionradiationpowergeneratedastheelectronbeamwasinlowdutycyclemode(theso-called tune-upmode);signalswithamplitudeoftheorderof1Vwereseeninthiscase.
drivelaserwhereasin(A),suchoperationwasproperlyperformed.Figure.5.14(C)whichreprecorrespondstothelongitudinalphasespacesetupusedfortherstFELlightgeneration.ThedifferencebetweenFigures(A)and(B)comesfromtheghostpulsebackground.In(B)theghostpulse wasnotcautiouslyminimizedbyproperlysettingtheelectro-opticscrystalofthephotocathode Figure.5.14(A)and(B)depictstwoautocorrelationmeasurementsperformedthesameday,it Autocorrelationmeasurement metricanddoesnotvanishwhenthepathlengthinthetwoarmsareidentical.Thisfaultwassentthealgebraicdierencebetweenthetwomeasurements,showsthattheonlydierencebetween thetwoaforementionedmeasurementsresidesinthepresenceofaDCosetforthecasewherethe ghostpulseisnotminimized.Thereforetheautocorrelationitselfisnotatallcontaminatedbythe ghostpulse. initiallythoughttobeduetoanonperfectorthogonalitybetweenthetwomirrorsinthetwo 18002=3600mcorrespondstothedistancebetweentheopticalvacuumwindowandtheplano- arms;wetriedtocorrectforitbyinstallingpiezoelectricpicomotorsonthemovablemirrorso managedtogettheinterferogramtovanishatthislocation.(2)Therearesecondarybumpslocated atapproximately1800mthatprobablycorrespondstoreectionsinthesystem(thedistance thatitstiltcanbeadjustedremotelywhileperformingameasurement.Unfortunatelywenever Fromtheseinterferogramswecanalsonoticeotherfeatures:(1)TheautocorrelationisnotsymtralpeakoftheinterferogramshowninFig.5.14(A).Fromthispeakwecandeducethermswidth('110m)andalsodistinguishwhetherthecoreofthebeamlongitudinaldistributionisagaussianlikeorsquare-likebunchdistribution.Forsuchapurposewehaveplottedonthesameguretheconvexlens).InFig.5.15(A)wepresentanescan(mirrorstepsizeforthedisplacementis5m)ofthecen- equivalentgaussianandsquaredistributionthathavethesameFWHMandthesameintegral. Asecondsetofexperimentsweperformedwastostudyhowsensitivethebunchlengthmeasurement thatconsistsofthesumofthetwopreviousdistributionsbettermatchestheinterferogramcore. DependenceoftheinterferogramonthebeamtransversesizeontheTRscreen Neitherofthesestandarddistributionsreallyttheinterferogramcore.Howeveradistribution waswithrespecttothebeamtransversesizeontheTRradiator.Theprocedureconsistedin withthecorrespondingtransversebeamsizesaregatheredinTab.5.5.5. varyinganupstreamquadrupoletriplettovarythebeamspotsizeatthepointofbunchlength proleandrmswidtharethencomputed.Theresultsofthemeasurementsforvedierentsettings oftheupstreamopticsarepresentedingure5.16whiletheFWHMoftheinterferogramalong theinterferometeroraCCDcamerabymovingthe\switchermirror".Theimagesrecordedbythe CCDcameraareprocessedaccordinglytothedescriptionofChapter3andthebeamtransverse measurement.Foreachsettingofthetripletwemeasured,atthesametime,thebeamtransverse spotsizeandthenthebunchlength.Forsuchpurposewecandirectthetransitionradiationto
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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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Page 94 and 95: Let'sassumethethinlensapproximation
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Page 109 and 110: Table4.7:Typicalsystematicerroronem
Page 111 and 112: 180 8 160 6 Figure4.22:Anexampleof2
Page 113 and 114: 4.0 3.5 3.0 2.5 Figure4.24:Emittanc
Page 115 and 116: Characterization LongitudinalPhaseS
Page 117 and 118: concentrateonthebeamparametersinthe
Page 119 and 120: 1.1 1 mrad 0.9 5 mrad mainlyduetoth
Page 121 and 122: Population Population 100000 90000
Page 123 and 124: Theequation5.8yields: f()=jZ+1 11Xn
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Page 133 and 134: FinallyitisinterestingtonotethatFou
Page 135: Itsautocorrelationis:S(z)=8>:(1=w2)
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Page 141 and 142: Asarstapproximation,wecanestimatetr
Page 143 and 144: errorpropagation8theoryappliedonEqn
Page 145 and 146: inducedbyspacechargeisnotaconcernin
Page 147 and 148: Golay Cell Signal (V) Golay Cell Si
Page 149 and 150: Golay Cell Ouput (V) Golay Cell Oup
Page 151 and 152: 150 100 5 4 Figure5.19:Energyspectr
Page 153 and 154: Figure5.23:picturaleectoflongitudin
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Page 157 and 158: σ x (m) x 10−3 5 4 3 2 1 0 0 5 1
Page 159 and 160: BeamDynamicsStudies Chapter6 undula
Page 161 and 162: x,y (mm) 6.0 4.8 3.6 2.4 1.2 x y 0.
Page 163 and 164: Space Charge over Emittance Ratio (
Page 165 and 166: numericalsolution[56].Thisapproxima
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Page 169 and 170: ε x (mm−mrad) Nominal 6 4 2 cryo
Page 171 and 172: 2.2 2 1.8 Figure6.10:Comparisonofth
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Page 185 and 186: Inthesecondseriesofrun,wewereableto
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Conclusion Chapter7 Therecirculator
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[2]Y.Shibata,T.Takahashi,T.Kanai,K.
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[29]J.-C.Denard,C.Bochetta,G.Traomb
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[65]B.C.Yunn,\ImpedancesintheIRFEL"
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TEM:transverseelectricmagnetic. TOF
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B.2Anoteonspacecharge Wedenetheslop
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B.3.3PARMELA FeaturesofJeersonLabVe
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Initialization MAIN Stop INPUT DECK
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C.0.6TheDispersionRelationsfor^S(!)
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have: Howeveritshouldbenotedthatweh
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FigureD.1:OverviewoftheRF-controlsy
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