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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1<br />
0.5<br />
0<br />
spreadoftheparticlewassetto:i!i+1=2Er<strong>and</strong>(1;1)where\r<strong>and</strong>"r<strong>and</strong>omlygenerate ofthewigglerwasnumericallysimulatedbygeneratinganenergyosetof:5MeV<strong>and</strong>theenergy anumberin[-1,1]interval.Thelongitudinalphasespaceaftertherecirculationfordierentvalues Figure3.9:<strong>Beam</strong>displacementinthebacklegtransportforarelativevariationof1%ofthemagnetic<br />
ofR56<strong>and</strong>T566.Thecorrespondingphasespaceafterthedecelerationinthelinacarepresented acceleration),thedownstream<strong>and</strong>upstreamthewigglerarepresentedintherstrow.Theeect eldoftherstrecirculationarc.<br />
−0.5<br />
energyspreadcanbegreatlyreduced,yieldingabeamthatcanbetransportedthroughthedump transferline. inthebottomrow.Itisseen(bottomright)thatwithproperchoiceofR56<strong>and</strong>T566,theresulting<br />
−1<br />
35 45 55 65 75<br />
Distance From the Cryomodule Exit (m)<br />
sigmamatrixelements).Thismatchingconditionisrequiredtoinsureonecanproducetheshortest possiblebunchlengthatthepointwheretheFEL-interactiontakesplace.Thisminimumbunch length,whenthematchingconditionisveried,isMIN Theoptimumpointforoperationofthelinacintermsofbothphase<strong>and</strong>acceleratingvoltagemust berelatedtothemomentumcompactionofthetransportfromthelinacexittothewigglerinorder toachievetherightlongitudinalphasespaceslopeattheentranceofthelinac.Infactthelinac ofthecompressorchicanebyfulllingtherelation:56=55=1=R56(56<strong>and</strong>55arethebeam voltage<strong>and</strong>phasearedictatedbythefactthatoneneedstomatchthelongitudinalphasetotheR56<br />
quadrupolesaswehavealreadymentioned.Anexampleofvariationofthemomentumcompaction ofonearcwithrespecttothesecondfamilyquadrupolesexcitationisshowningure3.11.Inthe freesystemtoadjusttheR56aretheend-looparcsoftherecirculationtransportbyvaryingthetrim about38MeV<strong>and</strong>isoperatedatapproximately-8dego-crest. emittance~"z<strong>and</strong>thebunchlength0zaretakenatthelinacexit. Fromparmelaoptimization8<strong>and</strong>recentexperimentaloperation,thelinacacceleratingvoltageis Theby-passchicaneshave<strong>their</strong>momentumcompactionxedbydesignto28:8cm<strong>and</strong>theonly z=R56~"z=0zwherethermslongitudinal<br />
gurewealsoplottedthenonlineartermT566forthequadrupolebutalsofordierentsextupoles 8B.C.Yunn,updatedparmelainputlesfortheIRFELdriver-accelerator,privatecommunications<br />
∆x (mm) for |∆E/E|=0.01
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