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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20<br />
18<br />
16<br />
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Figure4.14:Relativeerroroncomputedemittanceforthetwocasespresentedingure4.13versus<br />
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8<br />
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. 4 .<br />
quadscan with min=3m -x direction<br />
.<br />
quadscan with min=3m -y direction<br />
theemittancemeasurementbycodingthemeasurementprocedure[35],dataacquisition<strong>and</strong>data therelativeerroronbeamsizemeasurement.<br />
2<br />
quadscan with min=6m -x direction<br />
analysisinaCprogramwithaTcl/Tkuserinterface.Fromthisprogramtheuserdenethe ticetoachievedesiredbetatronfunctionvariationforoptimizingtheerrorbarsonthemulti-monitor measurements<strong>and</strong>sincewedesiredtohavethesamemethodtomeasureemittanceeverywherein theaccelerator,wedecidedtoonlyusethequadrupolescantechnique.Wetotallyautomated betatronfunctionvariation.Becausewendwecouldnotreliablysettheacceleratoropticallat-<br />
quadscan with min=6m -y direction<br />
0<br />
20 40 60 80 100 120 140 160 180 200<br />
programthenautomaticallyscanthequadrupolestrength.Foreachquadrupolesetting,thebeam quadrupole<strong>and</strong>viewershe/hedesirestouseforthemeasurement<strong>and</strong>fewotherparameters.The<br />
x,y ( m)<br />
prolemeasurementstationarecomputed<strong>and</strong>storedinale.Oncetheprogramhascompleted sizeontheOTRprolemonitor,thetransfermatrixbetweenthequadrupoleentrance<strong>and</strong>the thequadrupolescan,itcomputestheemittanceusingthealgorithmdetailedabove.Thisprogram canalsobeusedtopropagatethebeamparametersalongtheaccelerator<strong>and</strong>observethebeam envelope,usefulinformatione.g.toquantifylatticemismatch. Theprogramcanbedividedintothreeparts:(1)auserinterfacefromwhichtheuserentersparameters<strong>and</strong>readresultsofdataanalysis,(2)amachinemodel,Artemis8,thatisautomatically updatedtoreectthecurrentacceleratorsettings(magnetstrength,cavitygradient,...);<strong>and</strong>(3) subsystems(i.e.varyquadrupoles,inserttransitionradiationscreenintothebeampath,...). Atypicalemittancemeasurement,performedinthebacklegtransportlineforachargeperbunch of40pC,usingthequadrupolescanmethodispresentedingure4.17.Itshowsthevariationof acontroltoolboxthatcontainsaseriesofepics-protocolsequencesusedtocontrolthemachine 8theon-lineModelServerArtemiswasimplementedintheFELbySueWitherspoon<strong>and</strong>BruceBowling<br />
(%)<br />
.
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