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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5<br />
4<br />
3<br />
2<br />
Figure3.4:Exampleofcalibrationofacorrector.Theslopeofthelinearinterpolationis<br />
1<br />
0:0183mm=(G:cm)whichcorrespondstoanangulardeectionof6:54rad=(G:cm)<br />
0<br />
−1<br />
−2<br />
−3<br />
−4<br />
alongthebeamline;typicalvalueusedduringtheacquisitionofdierenceorbitmeasurementare ofthecalculatedvaluededucedfromthecorrectormagneticeldmapmeasurement3whichgivea<br />
−5<br />
excitationofthecorrector)alltheBPMreadbacksalongthebeamlineareacquiredthreetimes BPMvaluealongthebeamline,insuchawaythatthekickprovideasignicantpositionchange approximately100G:cm.ForagivencorrectorchangeBnom+B,(Bnomisthenominalmagnetic Practically,thecorrectorstrengthissetdevisobylookingattheon-linehistogramplotofthe kickof0:65mrad=(100Gauss:cm)<br />
−300 −200 −100 0 100 200 300<br />
Corrector Field Integral (G.cm)<br />
oflinearityofthesystem,theBPMreadbackshouldbetheoppositeoftheonemeasuredforthe latteroperationallowtovalidatethemeasurement,sinceforthelattercorrectorsetting,because (toquantifythebeampositionjitter).ThenthecorrectorissettothevalueBnomB.This<br />
2F04V<strong>and</strong>2F08V).Thecorrectorsarechosensothattherelativebetatronphaseadvancebetween forthehorizontalplane(2F00H,2F04H<strong>and</strong>2F08H)<strong>and</strong>threefortheverticalplane(2F00V, probedierentpartofthelattice.Inourpresentstudy,weusesixdierentcorrectors:three zeroforalltheBPMs. Theuseofonlyonecorrectortostudytheresponseofthelatticeisnotsucientsinceitonly\probe" thelatticeatlocationthathavearelativebetatronphaseadvanceofapproximately90deg4.Hence itispreferabletouseatleasttwocorrectorsseparatedbytheproperphaseadvancesothatthey rstmeasurement.Thereforethecomputationofthesumofthetwomeasurementsshouldgive<br />
istherelativebetatronphaseadvancebetweenthepointss<strong>and</strong>s0.<br />
3G.H.Biallas,privatecommunication,June99 4InthegeneralTwisstransfermatrixformalismonehas:Rs0!s 12=p(s)(s0)sin()where=(s)(s0)<br />
∆ x 2.80 meters downstream (mm)
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