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EXT Beam Measurements & Corrections

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EXT Beam Measurements & Corrections. Dispersion, Coupling, Beta Matching. ATF / ATF2 Schematic Layout. Emittance Measurement 5 × WS, 4 × OTR 10 μ W wires (x/y/+10°/-10°). Final Doublet. Coupling Correction. Final Focus. β -match. Dump. Inflector. Laserwire. EXT. INJ. Laserwire. - PowerPoint PPT Presentation

Text of EXT Beam Measurements & Corrections

Updates from ATF2

EXT Beam Measurements & CorrectionsDispersion, Coupling, Beta Matching

10th ATF2 Project Meeting, June 30 2010M. Woodley1/31110th ATF2 Project Meeting, June 30 2010

120 mS-bandRF Gun1.3 GeV S-band LinacDampingRingBeamTransportInflectorCouplingCorrection-matchFinal FocusDumpFinalDoubletEXTINJLaserwireXSRLaserwiree-IPBSM10 W wires(x/y)screenEmittanceMeasurement5 WS, 4 OTR10 W wires(x/y/+10/-10)PIP WS10 W wires(x/y/45)5 C wires(y/+1.3/-1.3)ATF / ATF2 Schematic Layout

FOBOM. Woodley2/3110th ATF2 Project Meeting, June 30 2010Injector system and Damping Ring can provide single-bunch beam or multi-bunch beamup to Q=210101-20 bunches per train1, 2, or 3 trainsMinimum Damping Ring emittances achieved (c.2004)x = 1.5 nmy = 4 pmY. Honda, et al., PRL92(2004)054802ParametersM. WoodleyparameterdesignMay 2010unitfrep1.561.56HzQ2-10~5109 e-/bunchE1.31.282GeVx (DR)3.04.810-6 my (DR)3.03.110-8 mx (EXT)1.21.9nmy (EXT)12.012.5pmz88mm0.080.08%x*4.0 40.0mmy*0.11.0mm'x*0.13940.1394radx*2.28.7my*37112nm3/31BX10BY10 relaxed FF optics310th ATF2 Project Meeting, June 30 2010M. WoodleyEMITTANCE & couplingMeasurement & Correction410th ATF2 Project Meeting, June 30 2010

XSRSRIFLW

00 modey = 4.1 m01 modey = 3.2 mATF2designy ~ 5 my ~ 5 mM. Woodley5/31from Kuroda-sans 9th ATF2 Project Meeting presentationLW: 00 is fundamental mode; 01 is higher-order modeXSR: vibration of grating mirror by RF waveguide air blowers (y always > 6 m) fixedSRIF: optical path realigned and enclosed in air-tight duct, slit separation increased by 50%, vibration reduced510th ATF2 Project Meeting, June 30 2010

QM7R: pole-tip radius = 16 mm extracted beam offset = 22.5 mmTokin 3393 ( = 32 mm)M. Woodley6/31extracted beam in coil pocket610th ATF2 Project Meeting, June 30 2010K1LK0LK2LQM7R replaced with larger bore ( = 42 mm) quadrupole in January 2009K1L = 0.3 m-1 = 0.76 nominal optics mismatch

K2L = 46.6 m-2 x-y coupling for vertically off-axis beam: factor ~ 2-3 y for y = 1 mm (x:y = 100:1)

Tokin 3393 ( = 32 mm)PRIAM simulationK1L = 0.392 m-1 = 0.99 nominalK2L = 1 m-2Tokin 3581 ( = 42 mm)

MeasuredM. Woodley7/3110th ATF2 Project Meeting, June 30 2010

BS3X roll = 4.66 mradIzv1 = -6.918 (-6.976) ampIzv2 = 1.270 ( 0.965) ampchi2 = 0.3102Observed that first 2 EXT vertical correctors (ZV1X and ZV2X) needed to be strong to properly launch into EXT (since before EXT rebuild for ATF2 )

hypothesize that correctors are compensating for a kick error in extraction channelsimulate error kick by rolling individual elements; use ZV1X and ZV2X to correct orbitfind error that gives best fit to actual ZV1X/ZV2X values BS3X septum magnet rollBS3X was physically rolled ~ -4 mrad (March 17, 2010) to relieve ZV1X and ZV2Xprojected vertical emittance in EXT before coupling correction was improved (~20-40 pm before ~10-20 pm after)

M. Woodley8/31BS3X rolled on March 17 2010vertical dispersion caused by BS3X roll + ZV1X/ZV2X correction was almost pure FD-phase810th ATF2 Project Meeting, June 30 2010M. WoodleyDateNwireEmit (nm)BMAGMay 18 201041.905 0.0781.08 0.03Apr 21 201041.212 0.0651.26 0.03Mar 17 2010BS3X rolled ~4 mrad (CCW)Feb 25 201041.868 0.3361.15 0.12Feb 17 20104negativeFeb 3 201041.626 0.0951.10 0.06Jan 28 2010Dec 8 200932.921 0.1291.05 0.03DateNwireEmit (pm)BMAGMay 18 2010511.7 2.31.43 0.25Apr 21 2010515.4 2.01.78 0.17Mar 17 2010BS3X rolled ~4 mrad (CCW)Feb 25 2010538.33 1.11.10 0.02Feb 17 2010522.6 1.41.15 0.04Feb 3 2010516.1 0.71.06 0.03Jan 28 2010531.6 1.21.03 0.01Dec 17 2009528.4 1.71.01 0.01Dec 8 2009432.2 1.91.35 0.13Horizontal EXT Emittance MeasurementsVertical EXT Emittance MeasurementsAnomalous DR EXT vertical emittance growth fixed (?)9/3110th ATF2 Project Meeting, June 30 2010

SQSQWSWSWSWSWS9090180909090 x y111728294243292978.210.3151.26.986.312.0149.36.884.312.1 (m)7 < x/y < 2210 wire orientation is optimal for beam tilt measurementSQSQOTROTROTROTRILC orthonormalcoupling correctionsystemM. Woodley10/3110th ATF2 Project Meeting, June 30 2010

projected vertical emittance (y) reduced to 11.5 pm using QK1Xrequired 57 individual wire scans per QK1X settingX (MW1X / MW2X / MW3X / MW4X) 3Y (MW0X / MW1X / MW2X / MW3X / MW4X) 3+10 (MW0X / MW1X / MW2X / MW3X / MW4X) 3-10 (MW0X / MW1X / MW2X / MW3X / MW4X) 3elapsed time: 7 hours for 5-point scan (!) need multi-OTR to speed uprealistically: 90 minutes for one 5-point QK scan (4 Y wires 3 scans at each point)

EmitY (pm)Coupling correction: single skew quadrupole scanM. Woodley11/31initial y (QK1X=0) 18 pmeach skew quad setting required 57 individual wire scans~1.5 minutes per scan11

Projected beam size measurements at x, 80o, y and 100o at 4 wire-scanner positions varying the strength of the QK1X skew quadrupole

Coupling reconstruction using:

Verification of the consistency of 80o and 100o measurements

Search for an algorithm to reconstruct the beam matrix at QK1X position:

The more reliable method consists of:Coupling measurements in ATF2 EXT (1) [Cecile Rimbault]

a. Constrain 6 elements with s33 fitsb. Constrain 3 elements with s13 fitsc. Constrain the last one with s11 fits

10th ATF2 Project Meeting, June 30 2010M. Woodley12/31Coupling measurements in ATF2 EXT (2) [Cecile Rimbault]

Comparison between measurements and beam matrix reconstruction result propagations33s13

at QK1X- physical results but large error bars (not to mention imaginary y!) large number of data sets is required to minimize statistical errorsanalysis algorithm must guarantee positive-definite beam matrix10th ATF2 Project Meeting, June 30 2010M. Woodley13/3110th ATF2 Project Meeting, June 30 2010M. Woodley

All 4 OTRs installed as of June 1Target inserters, movers, cameras, controls, software all OKAll 4 OTR targets melted during checkout!thin aluminized mylar target (1200 Al)Prosilica camera (3.75 m / pixel)14/3110th ATF2 Project Meeting, June 30 2010M. Woodleypixelspixels

pixelsATF2 EXT OTR1ok meltedJune 2, 2010single bunch beam Q 4109 e-/bunch (0.64 nC)1.56 Hzx 140 m ; y 10 m2 m nitrocellulose / 1200 Al~4 minutes in beam until damagedamaged targets will be replaced6 m kapton / 1200 Al100 m Al foil10 m tungsten X/Y wires will be added to target holdersscribeline15/31scribe marks must be aligned to absolute coordinate systemcameras are rotated until scribe lines are horizontal1510th ATF2 Project Meeting, June 30 2010M. WoodleyDispersionMeasurement & Correction1610th ATF2 Project Meeting, June 30 2010M. Woodley

Flight Simulator DispersionMeasurement / Correction17/3110th ATF2 Project Meeting, June 30 2010M. Woodley

Before Correction

After Correction

x'xIQF1X (amp)IQF6X (amp)Response Matrix MeasurementHorizontalDispersionCorrection18/3110th ATF2 Project Meeting, June 30 2010

QS1XQS2XSum-Knob: IQS1X = IQS2X

Simulated y* (right) and 'y* (right),back-propagated from IPVertical Dispersion Correction(FD-phase) Sum-Knob = -0.15 AIP-phaseFD-phaseM. Woodley19/3110th ATF2 Project Meeting, June 30 2010M. Woodley2010/ 2/ 18 10mm at IP The old orbit had a large offset around QF21X, QM16FF.I applied careful orbit tuning around QF21X, QM16FF with FF mover.2010/ 2/ 25 1mm at IP 2010/ 3/ 18 2mm at post-IP We used the fast kicker for the beam extraction.We switched back to SLAC kicker.2010/ 4/ 7 3.8mm at post-IP

2010/ 4/ 8 3.6mm at post-IP 3.6mm at IP

Dispersion for 4/7 QS1X= -1A QS2X= -1A Dispersion for 4/8 QS1X= -2.8A QS2X= -2.8A Summary of Vertical Dispersion at IPIP dispersion is not sensitive to Sum-knob From Okugi-sans presentation (ATF Ops 2010.04.09)20/3110th ATF2 Project Meeting, June 30 2010M. WoodleyBETA MATCHING2110th ATF2 Project Meeting, June 30 2010M. Woodley

RI =waist shiftmagnificationphase shift (* 0)alphaknobbetaknobphaseknobIrwin Knobs for -matching : R = RI R0Irwin Knobs

R0Final Focus22/3110th ATF2 Project Meeting, June 30 2010M. Woodley

get initial magnet strengths from control system, compute R0for a desired knob type, compute RI(n) for a small step in s, m, or small steps required due to nonlinear KLQ/Knobset R=RI(n)*R0 to make one knob stepuse MAD matching to fit to desired elements of R using FF matching quadrupoleschanges to magnet strengths tend to be symmetric in the knob value computed strengths for quadrupoles that start at zero tend to go bipolartried waist shift and magnification knobs during tuning week seem OK23/3110th ATF2 Project Meeting, June 30 2010M. Woodley

QM*FF Currents (amps)IP Twiss Parameters

Vertical Waist Scan (5*) [BX10BY10 optics]24/3110th ATF2 Project Meeting, June 30 2010M. WoodleyVertical Magnification Scan (0.5-2) [BX10BY10 optics]QM*FF Currents (amps)IP Twiss Parameters

25/3110th ATF2 Project Meeting, June 30 2010M. WoodleyQM*FF Currents (amps)IP Twiss ParametersVertical Phase Scan (0-90) [BX10BY10 optics]

26/3110th ATF2 Project Meeting, June 30 2010M. Woodley

R0QK1XQK2XQK3XQK4XRI =

Irwin Knobs for coarse coupling correction: R = RI R027/31skew quad acts at FD phase b ~ x-y coupling at IP, d ~ x'-y coupling at IP2710th ATF2 Project Meeting, June 30 2010Summary (1)improvements made to both hardware and diagnostics may have cured the anomalous vertical emittance growth at extraction from the Damping Ring that has been observed for many yearsQM7R replacementBS3X rollDR emittance diagnostics (XSR, SRIF, LW)the new EXT multi-OTR system should improve our ability to measure and correct emittancefaster emittance measurement and skew quad optimizationpossibility of 4D beam-matrix measurement / reconstruction / correctionFlight Simulator dispersion measurement / correction softw