[email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory...
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LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
LCLS Undulator Alignment and Motion ReviewLCLS Undulator Alignment and Motion Review
Beam-Based Alignment (BBA)Beam-Based Alignment (BBA)Paul Emma, SLACPaul Emma, SLAC
Oct. 21, 2005Oct. 21, 2005
LCLS Undulator Alignment and Motion ReviewLCLS Undulator Alignment and Motion Review
Beam-Based Alignment (BBA)Beam-Based Alignment (BBA)Paul Emma, SLACPaul Emma, SLAC
Oct. 21, 2005Oct. 21, 2005
Brief Review of MethodBrief Review of Method SimulationsSimulations Drift TolerancesDrift Tolerances
Brief Review of MethodBrief Review of Method SimulationsSimulations Drift TolerancesDrift Tolerances LCLSLCLS
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
MotivationMotivation
For SASE FEL at 1.5 For SASE FEL at 1.5 ÅÅ::Electron trajectory through undulator needs to be straight Electron trajectory through undulator needs to be straight to <5 to <5 m over ~10 m,m over ~10 m,
Traditional survey methods inadequate here,Traditional survey methods inadequate here,
BPM data acquired for several beam energies (14, 7.0, BPM data acquired for several beam energies (14, 7.0, 4.5 GeV) can resolve this level,4.5 GeV) can resolve this level,
Beam-based, energy-variation method is sensitive to all Beam-based, energy-variation method is sensitive to all fields, not just misaligned quadrupole magnetsfields, not just misaligned quadrupole magnets
For SASE FEL at 1.5 For SASE FEL at 1.5 ÅÅ::Electron trajectory through undulator needs to be straight Electron trajectory through undulator needs to be straight to <5 to <5 m over ~10 m,m over ~10 m,
Traditional survey methods inadequate here,Traditional survey methods inadequate here,
BPM data acquired for several beam energies (14, 7.0, BPM data acquired for several beam energies (14, 7.0, 4.5 GeV) can resolve this level,4.5 GeV) can resolve this level,
Beam-based, energy-variation method is sensitive to all Beam-based, energy-variation method is sensitive to all fields, not just misaligned quadrupole magnetsfields, not just misaligned quadrupole magnets
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
The MethodThe Method
BPM readings, BPM readings, mmii, written as sum of upstream kicks , written as sum of upstream kicks ++ offset, offset, bbii
Kicks are sensitive to momentum, Kicks are sensitive to momentum, ppkk, while offsets, , while offsets, bbii, are not, are not
BPM readings, BPM readings, mmii, written as sum of upstream kicks , written as sum of upstream kicks ++ offset, offset, bbii
Kicks are sensitive to momentum, Kicks are sensitive to momentum, ppkk, while offsets, , while offsets, bbii, are not, are not
ss
bbii > 0 > 0
EE = 0 = 0
EE < 0 < 0quad offsets and/or pole errorsquad offsets and/or pole errors
iithth BPM BPM jj
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Reference line defined by incoming Reference line defined by incoming xx00, , xx00 launch conditions launch conditionsReference line defined by incoming Reference line defined by incoming xx00, , xx00 launch conditions launch conditions
...The Method...The Method
1/1/pp
mmii
offset = bi
(15 GeV/c)(15 GeV/c)11 (7.0 GeV/c)(7.0 GeV/c)11 (4.5 GeV/c)(4.5 GeV/c)11pp
linear only if linear only if CCijij independent of independent of pp
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Schematic layout before BBA (cartoon example)Schematic layout before BBA (cartoon example)
~300 ~300 mm
UNDULATORUNDULATOR(132 m)(132 m)
LINACLINACbest final trajectorybest final trajectory
steering elementssteering elements
xx00xx00
initial incoming initial incoming launch errorlaunch error
Undulator misaligned w.r.t. linac axis Undulator misaligned w.r.t. linac axis with uncorrelated and correlatedwith uncorrelated and correlated** (‘random walk’) component(‘random walk’) component
* suggested by C. Adolphsen* suggested by C. Adolphsen
BPMsBPMsquadsquads
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Final trajectory after BBA (cartoon example)Final trajectory after BBA (cartoon example)
LINACLINAC
Beam is launched straight down undulator, Beam is launched straight down undulator, with possible inconsequential kink at boundarywith possible inconsequential kink at boundary
dispersion generated is insignificantdispersion generated is insignificant
Quadrupole magnets moved onto straight line and BPM offsets Quadrupole magnets moved onto straight line and BPM offsets subtracted in software, while undulators track quadrupolessubtracted in software, while undulators track quadrupoles
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Input errors used for simulationInput errors used for simulation
100100
100100
0.040.04
0.50.5
200200
200200
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Initial BPM and quad misalignments (w.r.t. linac axis)Initial BPM and quad misalignments (w.r.t. linac axis)
++ Quadrupole Quadrupole positionspositions BPM BPM offsetsoffsets
quad positionsquad positions
BPM offsetsBPM offsetsNow launch Now launch beam beam through through undulatorundulator
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Initial trajectory before any correction appliedInitial trajectory before any correction applied
++ Quadrupole Quadrupole positionspositionsoo BPM BPM readbackreadback ee trajectory trajectory
‘‘real’ trajectoryreal’ trajectory
quad positionsquad positions BPM readingsBPM readings
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
After weighted steering – prior to BBA procedureAfter weighted steering – prior to BBA procedure
++ Quadrupole Quadrupole positionspositionsoo BPM BPM readbackreadback ee trajectory trajectory
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
After 1st pass of BBA (13.6 GeV)After 1st pass of BBA (13.6 GeV)
++ Quadrupole Quadrupole positionspositionsoo BPM readback BPM readback ee trajectory trajectory
3322°3322° 3322°3322°
xx 44 44 mmxx 44 44 mm
yy 33 33 mmyy 33 33 mm
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Steering coils used for small, final corrections…Steering coils used for small, final corrections…
7 7 mm
Use steering coils for final Use steering coils for final iterations (quad move iterations (quad move
equivalent down to 0.5 equivalent down to 0.5 m)m)
Use steering coils for final Use steering coils for final iterations (quad move iterations (quad move
equivalent down to 0.5 equivalent down to 0.5 m)m)
BPM BPM
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
After 3rd pass of BBA (13.6 GeV)After 3rd pass of BBA (13.6 GeV)
++ Quadrupole Quadrupole positionspositionsoo BPM readback BPM readback ee trajectory trajectory
RON RON (FEL-code) (FEL-code) simulation shows simulation shows LLsatsat increased by increased by
<1 gain-length;<1 gain-length;R. Dejus, R. Dejus, N.VinokurovN.Vinokurov
98°98° 98°98°
xx 3.2 3.2 mmxx 3.2 3.2 mm
yy 2.5 2.5 mmyy 2.5 2.5 mm rms beam size: rms beam size: 36 36 mm
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Run BBA on 25 Different Random SeedsRun BBA on 25 Different Random Seeds
1-1-mm BPM BPM resolution + resolution + 100-100-mm initial initial BPM & quad BPM & quad offsetsoffsets
xx,,yyxx & & yy mover mover distrib.distrib.
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
FEL code evaluation of BBA simulation results...FEL code evaluation of BBA simulation results...
B. Fawley, H.-D. Nuhn, S. Reiche, PEB. Fawley, H.-D. Nuhn, S. Reiche, PE
FEL Saturation FEL Saturation Power at 1.5 Power at 1.5 ÅÅ
FEL Saturation FEL Saturation Length at 1.5 Length at 1.5 ÅÅ
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Alignment drift during BBA procedure…Alignment drift during BBA procedure…
Quadrupole and BPM alignment may change Quadrupole and BPM alignment may change during BBA procedure.during BBA procedure.
One iteration of BBA procedure will require <1 hr One iteration of BBA procedure will require <1 hr after full development and experience.after full development and experience.
Simulate alignment drift during BBA, using Simulate alignment drift during BBA, using 2.5-2.5-m quad and BPM (separately) changes, which m quad and BPM (separately) changes, which are uncorrelated are uncorrelated
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
2.5-2.5-m uniform quad and BPM changes during BBA procedurem uniform quad and BPM changes during BBA procedure2.5-2.5-m uniform quad and BPM changes during BBA procedurem uniform quad and BPM changes during BBA procedure
++ Quadrupole Quadrupole positionspositionsoo BPM readback BPM readback ee trajectory trajectory
167°167° 167°167°
REQUIRE:REQUIRE:< < 2 2 mm quad/BPM quad/BPM stability stability over over 1 hr1 hr
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Allow Allow 5-5-m uniform quad and BPM drift over long term (24 hrs)m uniform quad and BPM drift over long term (24 hrs)Allow Allow 5-5-m uniform quad and BPM drift over long term (24 hrs)m uniform quad and BPM drift over long term (24 hrs)
After beam-based alignmentAfter beam-based alignment10 10 m quad and BPM driftm quad and BPM driftMICADO steering appliedMICADO steering applied
Tolerance set at Tolerance set at 5 5 m over 24 hrsm over 24 hrs
LCLS Undulator Alignment and LCLS Undulator Alignment and Motion Review , Oct. 21, 2005Motion Review , Oct. 21, 2005
Paul Emma, SLACPaul Emma, [email protected]@SLAC.Stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
SummarySummary
LCLSLCLS
BPMs resolve trajectory to 1-2 BPMs resolve trajectory to 1-2 m rmsm rmsQuad positions and BPM readings ‘drift’ <2 Quad positions and BPM readings ‘drift’ <2 m over 1-hr m over 1-hr procedureprocedureTrajectory is stable to <20% of beam size (already Trajectory is stable to <20% of beam size (already demonstrated in FFTB)demonstrated in FFTB)BBA procedure repeated no more than once per week BBA procedure repeated no more than once per week given given 5 5 m drift tolerancem drift tolerance
Alignment can be achieved at adequate level Alignment can be achieved at adequate level using beam-based technique, given that…using beam-based technique, given that…