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

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4<br />

2<br />

thepickupcavityislocateddownstreamthecryounitafteradriftinadispersion-freeregion. <strong>and</strong>2Dsupersh)atthepickupcavitylocatedintheinjectionchicane<strong>and</strong>(2)forthecasewhere Figure6.11:\R55"transfermapgeneratedwithparmelafor(1)dierentcavitymodel(3Dmaa<br />

0<br />

3D−MAFIA model<br />

−2<br />

2D−Superfish model<br />

MAFIA + Dispersion Free<br />

Table6.1:Nominalinjectorsettingsbeforetherstseriesmeasurement. Buncherzero-crossing0.28MV/m ElementsPhase Laser Cavity#4on-crest Cavity#3-20dego-crest9.10MV/m referencephaseN/A Gradient 11.8MV/m<br />

−4<br />

−40 −20 0 20 40<br />

Drive Laser Phase (RF−Deg)<br />

tooperatethebuncherat0.32MV/msinceitprovidesapatternveryclosetothesimulatedone.<br />

AsecondseriesofmeasurementwasperformedaftertheFELphotonbeamwasoptimizedfor imentalphase-phasecorrelationpatternwiththesimulatedoneoccursforabunchergradientof approximately0.32MV/m;suchagradientdoesnotcorrespondtotheminimumenergyspreadon thedispersiveviewer. Secondseriesofmeasurementsperformed Itisseenfromthegure6.10thatthe\best"bunchergradientdevisedbymatchingtheexper-<br />

60pC/bunch6.Thevalueforthephases<strong>and</strong>gradientsrecordedbeforethemeasurement,after theFELwasoptimized,aregatheredintable6.2.Thephase-phasepatternmeasurediscompared ingure6.13withthe\ideal"oneobtainedbynumericalsimulations.Theagreementbetweenthe measurement<strong>and</strong>simulationisexcellent.Thisagreementvalidatesthemethodforsettingup thelongitudinaldynamicsmanipulationintheIRFELinjector.Basicallythetechniqueconsistsof 6thisoptimizationconsistedofmaximizingtheoutputFELpowerbyvaryingthebunchergradient<br />

T−O−F. at Pickup cavity (RF−Deg)

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