first opacs and beam dynamics studies on the max iv 3 gev...
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MAXIVFacility→h0p://www.maxiv.lu.se/WEPAB075,IPAC'17,Copenhagen,DENMARK,May14–19,2017
Top-upInjecAon&SlowOrbitFeedback•MAXIV3GeVstorageringisthefirstMBA-basedlightsourcetogointoopera7on;beamcommissioningstartedAug2015.
•FirststoredbeamonSep15,stackingachievedOct8,firstlightonNov2(onfirstoftwodiagnos[cbeamlines).
•SinceNov2015runningwithtop-upinjec[onandclosedSOFBloop.
•FirsttwoIDs(2-mlong,18-mmperiodIVUs)installedFeb2016,gapsclosedto4.5mmandfirstdatatakenbyJune2016.
•FacilityinauguratedonJune21,2016,duringsummer2016installedoneIVWandtwoEPUs.
•Sofarpeakcurrentof198mAstored,highlyefficientinjec[on/stackingperformedwithonlyasingledipolekicker.
•Rou[nedeliveryof50mAforBLcommissioningandfirstexperiments.
IntroducAon
FirstOpAcsandBeamDynamicsStudiesontheMAXIV3GeVStorageRing
•Firstturnachievedwithallmagnetsatnominalsefngsfor3GeVaccordingtomagne[cmeasurementdataandallringcorrectorssettozero.•Singledipoleinjec[onkickerat~4mrad,withmanualcorrectortweakingeventuallyreached500turns.•Aierphasinginthreecavi[es(delivering15-20kWeach)couldstorebeam.•Reducinginjec[onkickervoltageallowedtoaccumulate4.3mA;aierrela[vephasing(maximizemeasuredfs)increasedstoredbeamcurrentandinjec[onrate.
FirstTurns,StoredBeam&Stacking
LinearOpAcsfromClosedOrbits(LOCO)
•Reducedkickerstrengthandop[mizedinjectorRFchoppertoachievehighcaptureefficiency➙raisedinjec[onratefrom0.5Hzto2Hz(limita[onto2Hzgivenbycommissioninglicense).•Startedtop-upinjec[oninNov2016➙strongincreaseofaccumulateddose;allowscontroloffillingpakerncontrol.•SOFB(relyingonall380correctors)runningsinceNov2016at~0.5Hz(MMLscript)➙orbitstabilityacrossIDstraights200-400nmrms.
†)Newaddress:LawrenceBerkeleyNa[onalLaboratory,Berkeley,CA94720,USA,SCLeemann@lbl.gov
•Symmetriza[on/balancingofop[csthroughLOCOusingBPMs,correctors,andallindependentpowersuppliesforuprightquadrupolegradients(noskewcorrec[onsyet).•Largestrequiredgradientchangeremainedbelow1.5%;individualquadshun[ngpossiblelater.•Aierseveralitera[ons,differencebetweenmeasuredandmodelORMaslowas0.7μmrms.
OpAcsTuning,ChromaAcity&DynamicAcceptance
Emi0ance&LifeAme•Firstmeasurementsonthefirstdiagnos[csbeamlinehaverevealed339±30pmradHemikanceand16±1pmradVemikance(κ=4.7%).•Ascommissioningprogressedintegratedlife[mehasincreasedfrom0.3Ahto2–3Ah(pressureimprovingasaccumulateddoseincreases,tuningoftheHCs).
S.C.Leemann†,M.Sjöström,Å.Andersson,MAXIVLaboratory,LundUniversity,SE-22100Lund,SWEDEN
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Beta
Funct
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[m]
Dis
pers
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]
s [m]
βxβyηx
Table 1: MAX IV 3GeV storage ring design parameters.Stored current I 500mACircumference C 528mMain RF frf 99.931MHzBare lattice emittance "0 328 pm radBetatron tunes ⌫
x
, ⌫y
42.20, 16.28Linear chromaticity (natural) ⇠
x
, ⇠y
�50.0, �50.2Linear chromaticity (corrected) ⇠
x
, ⇠y
+1.0, +1.0Linear momentum compaction ↵
c
3.06 ⇥ 10�4
Energy spread (natural) ��
0.769 ⇥ 10�3
Radiated power (bare lattice) U0 363.8 keV/turn
•BPMoffsetsdeterminedwithrespecttoneighboringsextupoles/octupoles(trimwindingsinuprightquadmode).•CheckedBPMoffsetsovermonthsintermsofreproducibility,drii,temperaturestability,currentdependence,etc.•Orbitcorrec[ontoBPMoffsetsresultsin<1μm(H)and<41μm(V)rmsorbit(fewerVCMsthanBPMs➙introducedweigh[ngacrossIDstraights).
BPMOffsets&OrbitCorrecAon
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Co
un
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BPMx offset [mm]
Mean: +64 µm, RMS: 114 µm
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-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4
Co
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BPMy offset [mm]
Mean: +51 µm, RMS: 108 µm
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set
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Mean: +64 µm, RMS: 114 µm
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BP
My
off
set
[mm
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s [m]
Mean: +51 µm, RMS: 108 µm
Figure 1: BPM o↵set results. Top: measured o↵sets downloaded to BPM units.
Bottom: histogram of BPM o↵sets.
0
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x [mm]
Mean: +0.01 µm, RMS: 0.54 µm
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m]
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Mean: +0.01 µm, RMS: 0.54 µm
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Mean: -1.61 µm, RMS: 41.07 µm
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Mean: -1.61 µm, RMS: 41.07 µm
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Co
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HCM [A]
Mean: +0.7 mA, RMS: 1.21 A
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Co
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VCM [A]
Mean: +65 mA, RMS: 1.49 A
Figure 2: Orbit correction to downloaded o↵sets. Top: closed orbit deviationsof corrected orbit. Middle: histogram of closed orbit deviations. Bottom: his-togram of required corrector strengths.
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Sto
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urr
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Net C
harg
e a
t 2 H
z [p
C]
Time
96% Capture Efficiency
2016-05-10
DCCT in 3 GeV Storage RingCT in 3 GeV Transfer Line
Figure 3: Current in storage ring (blue) and injected charge per shot from
linac transfer line (red) showing increased capture e�ciency as commissioning
progressed.
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Sto
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Gro
ss C
harg
e a
t 2 H
z [p
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Time
2016-06-11
DCCT in 3 GeV Storage RingCT in 3 GeV Transfer Line
Figure 4: Stored current (blue) and injected charge per shot from linac transfer
line (red) during top-up operation.
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Time
2016-04-20
DCCT in 3 GeV Storage Ring
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2016-04-20
SOFB on
DCCT in 3 GeV Storage Ring
Figure 5: Position readings from BPMs in ID straights. Left: results over a 12-hour period showing drift during decaying beam, jitter during top-up injection,and stable orbit while the SOFB is running. Right: magnified view over theperiod while the SOFB is running.
Table 2: Parameters for LOCO fitting (w/o skew quad terms).Parameter type No. of paremetersBPM gains (H + V) 189 + 189BPM coupling factors (H + V) 189 + 189Corrector strengths (H + V) 200 + 179Corrector coupling factors (H + V) 200 + 179Dipole gradients (PFSs) 2Quadrupole gradients 20⇥ 2 + 20⇥ 2 + 2
-1.2
-0.8
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∆k/
k [%
]
Power Supply Index
Dipole Gradients (PFSs)
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∆k/
k [%
]
Power Supply Index
QDend
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Power Supply Index
QF
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Power Supply Index
QFm
Figure 7: Required changes to quadrupole gradients according to results of theuncoupled LOCO fit.Figure 6: Plot of measured ORM.
0.192
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Fra
ctio
na
l Tu
ne
(H
)
δ [%]
Measured dataFit: -43.79 δ2 + 1.027 δ + 0.1970
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Fra
ctio
na
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(V
)
δ [%]
Measured dataFit: 5.875 δ2 + 1.131 δ + 0.2723
Figure 10: Measured chromaticity: horizontal (top) and vertical (bottom).
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m]
BPM Index
Measured − Design
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MeasuredDesign
Figure 9: Horizontal dispersion beating (top) and spurious vertical dispersion(bottom) after downloading results of LOCO fitting to the quad power supplies.
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ta B
ea
t [%
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BPM position [m]
βx (RMS: 1.01%)
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Be
ta B
ea
t [%
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BPM position [m]
βy (RMS: 0.93%)
Figure 8: Remaining beta beat after downloading results of the LOCO fit tothe quad power supplies: horizontal (top) and vertical (bottom).
•AierLOCOadjustmentstunesmatchdesigntobekerthan0.01,betabea[ngis~1%rmsinbothplanes,horizontaldispersionbea[ngsuppressed.•Spuriousver[caldispersionandbetatroncouplingremaintobecorrected(skewquadcorrec[on).•IVUFFtablesrecordeddownto4.5mmgap;atclosedgaps~1umrmsorbitrecorded(withSOFB);localandglobalop[cscorrec[onforIVUsremaintobeimplemented(nosignsofbetabea[ngobservedsofar).•Linearchroma[ci[escorrectedto+1inbothplanes;2ndordertermsagreereasonablytodesign.•Scrapermeasurementshaverevealedlife[mecontribu[onsandeffec[vepressures;togetherwithlocalbetafunc[onmeasurementsoverallmachineacceptancehasbeendetermined➙7.0mmmradinH&2.5mmmradinVagreeverywellwithtrackingstudyresults.
Figure 11: Top: vertical scraper measurement at 70 mA, fits for gas and Tou-
schek lifetime contributions are included. Bottom: comparison of DA simulation
results at the center of a long straight (blue) with acceptances determined from
scraper measurements (red).
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y [m
m]
x [mm]
Ideal machine, δ=0.0%Machine with errors, δ=0.0%
Vacuum ChamberPhysical Aperture
Measured: Ax=7 mm mrad, Ay=2.5 mm mrad
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5Vertical scraper distance from beam center, dscry [mm]
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total dscry > dydscry = dyMeasurement
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