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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σ z (mm)<br />
0.2<br />
0.1<br />
Figure6.15:Variationofthebunchlengthversusthelinacacceleratingphaseperparmelasimu-<br />
0.1<br />
0<br />
−15 −10 −5 0 5 6 7 8 9<br />
lation(A)<strong>and</strong>measured(B)["measured"meansthebunchdistributionwasrecoveredfromthe<br />
∆φ (Deg) (parmela)<br />
∆φ (Deg) (experiment)<br />
CTRautocorrelationusingthetechniquementionedinChapter5].Comparisonbetweentheex-<br />
4<br />
3<br />
(C) Simulation<br />
(D)<br />
3<br />
2<br />
2 Measurement<br />
1<br />
1<br />
extentenergyspread)degradationinthebendingsystemoftheIRFEL.Forsuchapurposeswe perimental<strong>and</strong>simulatedbunchlongitudinaldistribution(C).TotalCTRpowersignalmeasured<br />
0<br />
0<br />
needtoconsiderinthefewfollowingsectionswhatarethemechanismsthatcanleadtoanincrease duringplot(B)experiment(D).<br />
−0.4 −0.2 0 0.2 0.4 5 6 7 8 9<br />
oftheemittance.Itseemswec<strong>and</strong>ividesuchmechanismintotwocategories:therstonearedue Inthislastsectionwewouldliketoreportonanattempttomeasureemittance(<strong>and</strong>toalesser 6.4StudyofPotentialEmittanceGrowth<br />
z (mm)<br />
∆φ (Deg) (experiment)<br />
tothelattice(betatronmismatch,lamentation,chromaticity);thesecondtypeareduetobunch selfinteraction(becauseofCoulombeldorradiationeld). Agrowthofemittancecomesfromanincreaseofoneoftheposition<strong>and</strong>/ordivergence,i.e.xorx0 inthex-x0phasespace.Let'sstartwithaninitialemittanceattheentranceofabeamlinesection Ifweassume,thatduetoperturbationinthebeamlinesection,theposition<strong>and</strong>divergenceofa particlechangeaccordinglyto: ~"0:8<br />
8Wevoluntaryomitthesubscriptxfortheemittance.inthissection<br />
~"0=hx20ihx02ihx0x0i21=2 x0!x0+x (6.17)<br />
Bunch Population (a.u)<br />
0.4<br />
0.3<br />
(A)<br />
σ z (mm)<br />
CTR signal (Volts)<br />
0.4<br />
0.3<br />
0.2<br />
(B)<br />
x0!x0+x0 (6.18)
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