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P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Linac CommissioningLinac CommissioningP. EmmaP. Emma
LCLSLCLS Commissioning Workshop, SLAC Commissioning Workshop, SLAC Sep. 22-23, 2004Sep. 22-23, 2004
LCLSLCLS
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Linac Commissioning Document AvailableLinac Commissioning Document Available
http://www-ssrl.slac.stanford.edu/lcls/linac/notes/linac_commissioning.ps
>23 page >23 page DRAFTDRAFT document describing: document describing:initial checkoutinitial checkoutsetup of linacsetup of linachow/where to measure beamhow/where to measure beamwhat device to scan and by how muchwhat device to scan and by how muchexpected resolutionexpected resolutionhow/where to correct beamhow/where to correct beametc…etc…
(not complete yet, but close)(not complete yet, but close)
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Linac ‘Commissioning’ (Physics)Linac ‘Commissioning’ (Physics)
Initial checkout (tunnel and beam-based)Initial checkout (tunnel and beam-based)
How to setup How to setup IIpkpk = 3.4 kA, = 3.4 kA, 1.2 1.2 m, etc.m, etc.
What to measure and what to adjust (simulations)What to measure and what to adjust (simulations)
Longitudinal phase spaceLongitudinal phase spaceBunch LengthBunch Length
Energy Spread (proj. & slice)Energy Spread (proj. & slice)
Transverse phase spaceTransverse phase spaceProjected EmittanceProjected Emittance
Slice EmittanceSlice Emittance
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Initial Machine ConditionsInitial Machine Conditions
Magnets warmed, standardized, and set properlyMagnets warmed, standardized, and set properly
Reasonable quality Reasonable quality ee beam available: beam available:
Rough beam steering establishedRough beam steering established
Rough RF phasing of each klystron (1 or 2 deg)Rough RF phasing of each klystron (1 or 2 deg)
Any beam obstruction and loss issues solvedAny beam obstruction and loss issues solved
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Initial Checkout - Initial Checkout - TUNNELTUNNEL
Power-on Power-on polarity checkspolarity checks of all “new” magnets of all “new” magnets
Validate proper Validate proper cabling connectionscabling connections (magnets, (magnets, BPMs, diagnostics…)BPMs, diagnostics…)
Rough Rough alignment inspectionalignment inspection (tape measure, eye) (tape measure, eye)
Verify all insertable devices move in and out, and Verify all insertable devices move in and out, and are finally are finally removedremoved
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Initial Checkout - Initial Checkout - BEAM-BASEDBEAM-BASED
Take Take full setfull set of of xx and and yy ‘oscillation’ data (checks ‘oscillation’ data (checks optics and BPM scaling…)optics and BPM scaling…)
Verify all Verify all profile monitor scalingprofile monitor scaling with known with known centroid shifts (wires, OTR, YAG, screens…)centroid shifts (wires, OTR, YAG, screens…)
Repeat above at high dispersion points (DL1, BC1, Repeat above at high dispersion points (DL1, BC1, BC2, DL2) using energy changesBC2, DL2) using energy changes
CalibrateCalibrate all BPM-charge, and toroid readings all BPM-charge, and toroid readings based on one well established referencebased on one well established reference
DocumentDocument all the above for future scrutiny all the above for future scrutiny
CHECKOUT CHECKOUT MUSTMUST BE COMPLETEBE COMPLETE BEFORE MEASUREMENTS AND TUNING BEGIN! BEFORE MEASUREMENTS AND TUNING BEGIN!
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Location of Main Linac DiagnosticsLocation of Main Linac Diagnostics5+ energy spread meas. stations (optimized with small 5+ energy spread meas. stations (optimized with small ))
...existing linac...existing linac
L0L0
rfrfgungun
L3L3L1L1 XX L2L2
xx,,yy xx,,yy xx,,yy xx,,yy
xx,,yy
EE EE EEEE
5+ emittance meas. stations designed into optics (5+ emittance meas. stations designed into optics (xx,,yy))BPMs at or near most quadrupoles and in each bend syst.BPMs at or near most quadrupoles and in each bend syst.
RF deflectors for slice RF deflectors for slice and and EE measurements (L0 & L3) measurements (L0 & L3)
EE
EE EEEEEE EE
T-cav.T-cav.
T-cav.T-cav.
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Setup of Linac-0 RFSetup of Linac-0 RF
RF-deflector at 1 MVRF-deflector at 1 MV
Phasing L0-LinacPhasing L0-Linac
RF-deflectorRF-deflector
yy bunch length bunch length
minimize energy spread with L0 RF phaseminimize energy spread with L0 RF phase
Establish initial bunch lengthEstablish initial bunch lengthPhase linac-0Phase linac-0
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Setup of Linac-1 RFSetup of Linac-1 RF
Linac-1 RF phase scanLinac-1 RF phase scan(X-band off, BC1 bends at 295 MeV)(X-band off, BC1 bends at 295 MeV)
Linac-X RF phase scanLinac-X RF phase scan(BC1 bends at 250 MeV)(BC1 bends at 250 MeV)
set phase to set phase to 2525˚̊0.50.5˚̊ set phase to set phase to 160˚160˚0.5˚0.5˚
20-20-m res. BC1 BPMm res. BC1 BPM 20-20-m res. BC1 BPMm res. BC1 BPM
L1 RF phaseL1 RF phase
LX RF phaseLX RF phase
Turn on BC1 energy feedbackTurn on BC1 energy feedbackSwitch off BC2 chicaneSwitch off BC2 chicaneUse sec-25 RF-deflector to meas. bunch length (Use sec-25 RF-deflector to meas. bunch length (zz11))
Adjust S-band RF phase (Adjust S-band RF phase (0.50.5˚̊) to set ) to set zz11 195 195 10 10 mm
Linac-1Linac-1newnew
rfrfgungun
21-1b21-1b21-1d21-1d XX
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Setup of Linac-2 RFSetup of Linac-2 RF
Linac-2 RF phase scanLinac-2 RF phase scan(BC2 bends at 5.9 GeV, or…)(BC2 bends at 5.9 GeV, or…)
set phase to set phase to 4141˚̊0.50.5˚̊
40-40-m res. BC2 BPMm res. BC2 BPM
L2 RF phaseL2 RF phase
Turn on BC2 energy feedbackTurn on BC2 energy feedbackUse sec-25 RF-deflector to measure length (Use sec-25 RF-deflector to measure length (zz22))
Adjust L2 RF phase (Adjust L2 RF phase (0.50.5˚̊) to set ) to set zz22 20 20 2 2 mm
Linac-3 phasing is trivial (Linac-3 phasing is trivial (5˚)5˚)
5-5-m res. LTU BPMm res. LTU BPM
L2 phaseL2 phase
Scan Linac-2 phase & use LTU BPM to find Scan Linac-2 phase & use LTU BPM to find max. wake-induced energy loss across Linac-3max. wake-induced energy loss across Linac-3
(NO CSR)
L2L2 L3L3
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Emittance Meas. Simulation in LCLSEmittance Meas. Simulation in LCLS
OTR1,2,3OTR1,2,3 WS11,12,13WS11,12,13BC1BC1
Multiple OTR screensMultiple OTR screensMultiple wire-scannersMultiple wire-scanners
Quad-scans on single OTRQuad-scans on single OTRQuad-scans on OTR with RF-deflectorQuad-scans on OTR with RF-deflector
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
135-MeV OTR 135-MeV OTR xx-profiles from tracking-profiles from tracking
xx = 0.75 = 0.75 ±± 0.04 0.04 mmxx = 0.75 = 0.75 ±± 0.04 0.04 mm
xx 118 118 mm xx 49 49 mm
xx 120 120 mm
non-Gaussiannon-Gaussian
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
xx-Slice-Emittance Measurement-Slice-Emittance MeasurementRF-deflector at 1 MVRF-deflector at 1 MV
slice OTR 10 timesslice OTR 10 times
yy bunch length bunch length
““QE03” quad scannedQE03” quad scanned
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
xx-Slice-Emittance Measurement Simulation-Slice-Emittance Measurement Simulation
slice-5slice-5
Injector at 135 MeV with Injector at 135 MeV with S-band RF-deflector at 1 MVS-band RF-deflector at 1 MV
= meas. sim.= calc.= y distribution= actual(same SLAC slice-(same SLAC slice- code used at BNL/SDL)code used at BNL/SDL)
DL1 slice-emit on WS02DL1 slice-emit on WS02
“QE03” scanned 20% (centered on 106% of its nominal gradient)
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
yy-slice-Emittance Measurement in BC1-slice-Emittance Measurement in BC1
3.9 mm3.9 mm
0.1 mm
0.1 mm
““Q21201” scanned Q21201” scanned ±±20%20%
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
yy-slice-Emittance Measurement Simulation-slice-Emittance Measurement Simulation
slice-slice-yy emittance in emittance in
BC1 using BC1 using xx-chirp-chirp
= meas. sim.= calc.= y distribution= actual
slice-5slice-5
“Q21201” scanned 20% (centered on 92% of its nominal gradient)
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Empirical BC1/BC2 Dispersion CorrectionEmpirical BC1/BC2 Dispersion Correction
Residual Residual xx-dispersion (and its angle) is precision -dispersion (and its angle) is precision minimized using ‘tweaker’ quads in the chicaneminimized using ‘tweaker’ quads in the chicane
actual data from SPPS chicaneactual data from SPPS chicane
x /2
SPPS chicane with quadsSPPS chicane with quadsCorrect Correct and ( and (), orthogonally ), orthogonally with 2 quadswith 2 quads
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Transverse Wakefield CompensationTransverse Wakefield Compensation
trajectory trajectory afterafter steering steering
xx 2.1 2.1 mm
yy 5.2 5.2 mm
All quadrupoles, RF structures, and All quadrupoles, RF structures, and BPMs misaligned by 300 BPMs misaligned by 300 m rmsm rms
steering coilssteering coils
xx 1.0 1.0 mm
yy 1.1 1.1 mm
Small ‘bumps’ added to Small ‘bumps’ added to correct emittancecorrect emittance
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Repeat for 100 Different SeedsRepeat for 100 Different Seeds
// 20% (projected) 20% (projected)
M. BorlandM. Borland
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Energy Jitter Measurement (Feedback)Energy Jitter Measurement (Feedback)
undulator…undulator…
relative energy relative energy centroid resolution: centroid resolution:
~0.003%~0.003%
xx11 xx22Two 5-Two 5-m BPMs:m BPMs:
Difference of BPM Difference of BPM xx-readings is proportional to energy -readings is proportional to energy change, and change, and insensitiveinsensitive to incoming trajectory jitter. to incoming trajectory jitter.
xx 125 mm) 125 mm)
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Slice-Emittance Configuration for LTUSlice-Emittance Configuration for LTU
nominal opticsnominal optics(proj. emit.)(proj. emit.)
WS31-34WS31-34
undulator…undulator…
slice-emit.slice-emit.meas. opticsmeas. optics
OTR33OTR33stopperstopperinsertedinserted
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Slice-Emittance Measurements in LTUSlice-Emittance Measurements in LTU
= meas. sim.= calc.= y distribution= actual
xxxx
zz
yy
LTU at 14 GeV with S-band LTU at 14 GeV with S-band RF-deflector at 24 MVRF-deflector at 24 MV
“QEM3” (or tweaker) scanned 3% (centered on its nominal gradient)
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
Slice Energy Spread Measurements in LTUSlice Energy Spread Measurements in LTU
LTU at 14 GeV with S-band LTU at 14 GeV with S-band RF-deflector at 24 MVRF-deflector at 24 MV
FEL goalFEL goal
EE//E E 104
x 12 m
P. Emma, P. Emma, SLACSLAC LCLSLCLS Commissioning – Sep. 22, 2004 Commissioning – Sep. 22, 2004
SummarySummaryMost diagnostics incorporated into design and Most diagnostics incorporated into design and simulated (1simulated (1stst pass) pass)
Two RF-deflectors allow time resolved Two RF-deflectors allow time resolved measurements at low and high energymeasurements at low and high energy
Tune-up algorithms considered, but more Tune-up algorithms considered, but more refinement neededrefinement needed
Feedback systemsFeedback systems must maintain setup while must maintain setup while tuning progresses (bunch length monitors?)tuning progresses (bunch length monitors?)