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Beam-Based Alignment Results. Henrik Loos, for the LCLS Commissioning Team. Undulator Trajectory Requirements. Beam through undulator rms 2 μ m per gain length Undulator with 33 segments total 100 m Not possible with conventional alignment - PowerPoint PPT Presentation
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1 Henrik [email protected]
1Undulator BBA ResultsLCLS FAC, June 8, 2009
Beam-Based Alignment Results
Henrik Loos, for the LCLS Commissioning Team
2 Henrik [email protected]
2Undulator BBA ResultsLCLS FAC, June 8, 2009
Undulator Trajectory Requirements
Beam through undulator rms 2 μm per gain length
Undulator with 33 segments total 100 m
Not possible with conventional alignment
Use beam based alignment using set of different energies
RF BPM resolution < 1 μm
3 Henrik [email protected]
3Undulator BBA ResultsLCLS FAC, June 8, 2009
Undulator Configuration
Undulator, Quad, BPM, BFW move with girderBeam Finder Wire (BFW) retractableHorizontal translation of undulator
Complete retract (80 mm)Undulator K adjustment (± 5 mm)
In/Out
Scan
Beam
Undulator Quad RF BPM
Girder
BFWCorr
Girder Movers
K
4 Henrik [email protected]
4Undulator BBA ResultsLCLS FAC, June 8, 2009
Beam Based Alignment Principle
BPM offsets unknownMagnetic fields (earth, quad kicks, etc.) unknownCorrect field integrals with quad offsets or correctors for dispersion free trajectory at BPM positionTrajectory between BPMs remains unknownMeasure trajectory at different energies to extrapolate to straight line at infinite energyFixed undulator quad fieldsBPM position is BPM offset at infinite energy
5 Henrik [email protected]
5Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Measurement Schematic
Δq1 Δq3Δq2
Δb1 Δb3Δb2
Δy1 Δy3Δy2Δy0 Δy4
Δb0Δb0
E1
E2
BPM Offsets Δbi
Quad Offsets Δqi
x,x’
E1 < E2
6 Henrik [email protected]
6Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Procedure
Model beam position (yj) at BPMs as function of initial launch at 1st BPM (xi), quad offsets (Δqi), BPM offsets (Δbi)
y = [Rx Rq Rb] [x’ Δq’ Δb’]’
Rxj = Rj
1,1:2
Rqj = [R1,j
end - R1j
beg … Ri<j,jend
- Ri<j,j 0 … 0]11
Rb = -IFit solution for y arbitrary to adding linear function to quad and BPM offsetsAdd constraint equations for quad or BPM offsets
0 = Σi Δqi and Σi zi Δqi for linear quad offset constraint
0 = Δqi for minimum quad offset constraint
7 Henrik [email protected]
7Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Implementation
Setup accelerator for one energyCalculate response matrix for this energyMeasure N orbits at this energy and averageRepeat for all energiesGenerate final matrix with separate launch parameters for each energy and selected constraintsFit quad and BPM offsets and implementRepeat BBA procedure
8 Henrik [email protected]
8Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Simulation
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x P
os (
m)
BBA Scan Orbit 27-Feb-2009 00:07:31
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y P
os (
m)
Position z (m)
En = 4.30 GeV, x = 470.2 um
En = 6.54 GeV, x = 623.5 um
En = 13.64 GeV, x = 468.3 um
En = 4.30 GeV, y = 595.1 um
En = 6.54 GeV, y = 993.3 um
En = 13.64 GeV, y = 573.7 um
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BBA Scan Fit Result 27-Feb-2009 00:07:31
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y O
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Off
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Position z (m)
BPM Offset Fit
Quad Offset FitBPM Simul
Quad Simul
BPM Offset Fit
Quad Offset FitBPM Simul
Quad Simul
Error BPM Fit x
Error BPM Fit yError Quad Fit x
Error Quad Fit y
Simulation OrbitsSimulation Orbits Simulation Fit Lin. QuadSimulation Fit Lin. Quad
9 Henrik [email protected]
9Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 1st Run
First test: Energy range only 10 – 13.64 GeV50 orbits each, averagedBPMs not well calibratedLarge oscillation in fit of quad offset, 1mm error barAssume BPM offset worse than quad offsetApply instead constraint for minimal quad offsetInitial position rms 300 μm
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os (
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BBA Scan Orbit 16-Jan-2009 21:02:13
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os (
m)
Position z (m)
En = 10.00 GeV, x = 279.6 um
En = 11.50 GeV, x = 347.2 um
En = 13.64 GeV, x = 316.9 um
En = 10.00 GeV, y = 112.4 um
En = 11.50 GeV, y = 270.4 um
En = 13.64 GeV, y = 134.3 um
Measured OrbitMeasured Orbit
10 Henrik [email protected]
10Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 1st Run
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x O
ff (
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BBA Scan Fit Result 16-Jan-2009 21:02:13
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
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BBA Scan Fit Result 16-Jan-2009 21:02:13
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y O
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
Fit with Linear Quad ConstraintFit with Linear Quad Constraint Fit with Min. Quad ConstraintFit with Min. Quad Constraint
Applied this to BPM offsetsApplied this to BPM offsets
11 Henrik [email protected]
11Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 2nd Run
Energy range now 7 – 13.64 GeV
Still large ~1 mm oscillation on quad offset fit
Apply relaxed minimum quad constraint, 100 μm error bar
Orbits very similar after correction
Position rms ~50 μm after
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x P
os (
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BBA Scan Orbit 22-Jan-2009 11:36:38
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y P
os (
m)
Position z (m)
En = 7.00 GeV, x = 95.3 um
En = 9.25 GeV, x = 124.4 um
En = 13.64 GeV, x = 74.8 um
En = 7.00 GeV, y = 105.7 um
En = 9.25 GeV, y = 114.3 um
En = 13.64 GeV, y = 161.7 um
Measured OrbitMeasured Orbit
12 Henrik [email protected]
12Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 2nd Run
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ff (
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BBA Scan Fit Result 22-Jan-2009 11:36:38
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y O
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
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x P
os (
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BBA Scan Orbit 22-Jan-2009 15:18:37
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y P
os (
m)
Position z (m)
En = 7.00 GeV, x = 42.3 um
En = 9.25 GeV, x = 48.4 um
En = 13.64 GeV, x = 51.2 um
En = 7.00 GeV, y = 66.3 um
En = 9.25 GeV, y = 80.8 um
En = 13.64 GeV, y = 117.1 um
Fit with Min Quad Scale 20Fit with Min Quad Scale 20 Measured Orbit after CorrectionMeasured Orbit after Correction
13 Henrik [email protected]
13Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 3rd Run
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os (
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BBA Scan Orbit 07-Feb-2009 18:35:30
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y P
os (
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Position z (m)
En = 4.30 GeV, x = 44.8 um
En = 7.00 GeV, x = 31.2 um
En = 9.25 GeV, x = 26.9 um
En = 13.64 GeV, x = 18.9 um
En = 4.30 GeV, y = 15.9 um
En = 7.00 GeV, y = 18.2 um
En = 9.25 GeV, y = 16.2 um
En = 13.64 GeV, y = 12.2 um
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BBA Scan Fit Result 07-Feb-2009 18:35:30
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y O
ff (
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
Measured Orbit 4.3 – 13.64 GeVMeasured Orbit 4.3 – 13.64 GeV Fit with Linear Quad ConstraintFit with Linear Quad Constraint
14 Henrik [email protected]
14Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: 3rd Run
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os (
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BBA Scan Orbit 08-Feb-2009 00:02:30
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y P
os (
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Position z (m)
En = 4.30 GeV, x = 5.5 um
En = 7.00 GeV, x = 2.2 um
En = 9.25 GeV, x = 6.7 um
En = 13.64 GeV, x = 5.9 um
En = 4.30 GeV, y = 10.1 um
En = 7.00 GeV, y = 2.0 um
En = 9.25 GeV, y = 1.7 um
En = 13.64 GeV, y = 3.5 um
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BBA Scan Fit Result 08-Feb-2009 00:02:30
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ff (
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
Measured Orbit 4th IterationMeasured Orbit 4th Iteration Fit with Linear Quad ConstraintFit with Linear Quad Constraint
Position rms 2 – 10 μmPosition rms 2 – 10 μm Offset Error Bar 10 μmOffset Error Bar 10 μm
15 Henrik [email protected]
15Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: Best Orbit
Carefully calibrated BPMsEnergy range 4.3 – 13.64 GeV4 different energiesUndulator launch feedback onAverage position rms 1 – 2 μmBetatron jitter ~20 μm
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os (
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BBA Scan Orbit 09-Feb-2009 15:57:53
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os (
m)
Position z (m)
En = 13.64 GeV, x = 1.8 um
En = 13.64 GeV, y = 1.1 um
16 Henrik [email protected]
16Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA Results: Girder Bump Test
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os
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BBA Scan Orbit 21-May-2009 15:44:33
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y P
os
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Position z (m)
En = 4.30 GeV, x = 151.8 um
En = 7.00 GeV, x = 62.6 um
En = 9.25 GeV, x = 33.6 um
En = 13.70 GeV, x = 11.1 um
En = 4.30 GeV, y = 74.3 um
En = 7.00 GeV, y = 46.9 um
En = 9.25 GeV, y = 21.6 um
En = 13.70 GeV, y = 7.5 um
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BBA Scan Fit Result 21-May-2009 15:44:33
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y O
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Position z (m)
BPM Offset Fit
Quad Offset FitInitial Quad Offset
Initial BPM Offset
BPM Offset Fit
Quad Offset FitInitial Quad Offset-48um bump @ 13.7 GeV-48um bump @ 13.7 GeV
58um bump @ 13.7 GeV &-58um BPM offset
58um bump @ 13.7 GeV &-58um BPM offset
BBA procedure finds both quad offsets and BPM offsetsBBA procedure finds both quad offsets and BPM offsets
17 Henrik [email protected]
17Undulator BBA ResultsLCLS FAC, June 8, 2009
Typical BBA After Several Months
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os
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BBA Scan Orbit 30-May-2009 09:57:22
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y P
os
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Position z (m)
En = 4.30 GeV, x = 19.3 um
En = 7.00 GeV, x = 13.5 um
En = 9.25 GeV, x = 14.2 um
En = 13.50 GeV, x = 21.6 um
En = 4.30 GeV, y = 55.1 um
En = 7.00 GeV, y = 23.9 um
En = 9.25 GeV, y = 12.9 um
En = 13.50 GeV, y = 9.5 um
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BBA Scan Fit Result 30-May-2009 09:57:22
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ff
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Position z (m)
BPM Offset Fit
Quad Offset Fit
BPM Offset Fit
Quad Offset Fit
Some quad & BPM offsets in end region of undulator from incrementalorbit corrections (retracting undulators, changing of taper)
Some quad & BPM offsets in end region of undulator from incrementalorbit corrections (retracting undulators, changing of taper)
Observe mostly changes in BPM offsets ~ 10 – 30umObserve mostly changes in BPM offsets ~ 10 – 30um
18 Henrik [email protected]
18Undulator BBA ResultsLCLS FAC, June 8, 2009
Quad Alignment Measurement
8 8 m rmsm rmsEarth’s field effectEarth’s field effect
Z (m)Z (m)
undulators installed (with undulators installed (with -metal)-metal)
Measure quadrupole offset from beam axisVary quad magnetic field and fit offset to trajectory kickVerifies earth field compensation from BBA
P. Emma
19 Henrik [email protected]
19Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA User Interface
SimulationSimulation
MeasurementMeasurement
Fit OptionsFit Options
CorrectionsCorrections
20 Henrik [email protected]
20Undulator BBA ResultsLCLS FAC, June 8, 2009
Fast Linac Energy Change
User interface to run an automated scriptBlock/unblock beamActivate saved klystron configurationTrim saved magnet configurationToggles feedbacksEnables one BBA run in 10 - 15min (at best), ~2 – 4 h (worst)
21 Henrik [email protected]
21Undulator BBA ResultsLCLS FAC, June 8, 2009
BBA & Undulator Taper
Orbit effects from undulator motionNo earth field shielding with retracted undulatorUndulator translation (~80 mm) shifts entire girder by ~10 - 100 um (quad & BPM)Undulator field integral depends on taper
GoalStraight trajectory for all undulator translations
StrategyDo BBA at design taper, correct quad positionCompensate field integral change for different taper with corrector coilCompensate girder shift for retracted undulator with corrector coils and BPM offset
22 Henrik [email protected]
22Undulator BBA ResultsLCLS FAC, June 8, 2009
Undulator Field Integral Measurement
Apply 1st field integral to corrector coilApply 1st field integral to corrector coil
23 Henrik [email protected]
23Undulator BBA ResultsLCLS FAC, June 8, 2009
Summary
AchievedBBA procedure successfully implementedConverges to ~1 μm trajectory rmsImportant to have full energy rangeErrors on fitted quad offsets decreased from 1 mm to 10 μm with increasing energy rangeFast energy switching 15 min BBA possibleComplemented by measurement of quad offsets by varying quad strength
To DoFully automate energy change (Interface to energy management, orbit feedback in linac)Study BBA at low charge (< 250 pC)Implement orbit correction from undulator translationCompare girder position from BBA with alignment diagnostic system (ADS)Monitor and study BPM offset drifts
