Physics Performance Details [email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator Center

Undulator Systems Review, March 3 - 4, 2004Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRLHeinz-Dieter Nuhn, SLAC / SSRL

Physics Performance DetailsPhysics Performance Details [email protected]@slac.stanford.edu

Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center

Physics Performance DetailsHeinz-Dieter Nuhn, SLAC / SSRL

March 3, 2004

Physics Performance DetailsHeinz-Dieter Nuhn, SLAC / SSRL

March 3, 2004

Undulator OverviewUndulator Overview FEL Performance AssessmentFEL Performance Assessment Recent Undulator Parameter ChangesRecent Undulator Parameter Changes

Undulator OverviewUndulator Overview FEL Performance AssessmentFEL Performance Assessment Recent Undulator Parameter ChangesRecent Undulator Parameter Changes




Linac Coherent Light Source

Near Hall

Far Hall

Undulator




UNDULATOR

3,400 496

11,915 mm

Weak Horizontal Steering Coil

Weak Vertical Steering Coil

Beam Position Monitor

723 mm

Wire/OTR Region

Quadrupoles

LCLS Undulator Schematic (Regular Section)LCLS Undulator Schematic (Regular Section)LCLS Undulator Schematic (Regular Section)LCLS Undulator Schematic (Regular Section)

131,120 mmTotal Lattice Length

Total Device Length130,397 mm




Undulator Performance RequirementsUndulator Performance Requirements

ParameterParameter SymbolSymbol TargetTarget

(Nom.)(Nom.)UnitsUnits ToleranceTolerance

((criticalcritical))

Effective Undulator ParameterEffective Undulator Parameter KK 3.6303.630 ±0.015 ±0.015 %%

Average Gap HeightAverage Gap Height gg 6.56.5 mmmm

Average Period LengthAverage Period Length uu 30.0030.00 mmmm ±0.03±0.03

Wiggle PlaneWiggle Plane horizontalhorizontal ——

Trajectory Straightness ToleranceTrajectory Straightness Tolerance xx 22 mm ——

Segment Phase Slippage ToleranceSegment Phase Slippage Tolerance 1010 degreesdegrees ——




Tolerance Analysis: Tolerance Analysis: RONRONR. Dejus, N. VinokurovR. Dejus, N. VinokurovTolerance Analysis: Tolerance Analysis: RONRONR. Dejus, N. VinokurovR. Dejus, N. Vinokurov




Trajectory Straightness RequirementTrajectory Straightness RequirementTrajectory Straightness RequirementTrajectory Straightness Requirement

Preserve transverse overlap between beam and Preserve transverse overlap between beam and radiationradiation => Tolerance for betatron amplitude < 8 => Tolerance for betatron amplitude < 8 m (beam radius m (beam radius

dep.)dep.)

Avoid longitudinal phase slippage between beam and Avoid longitudinal phase slippage between beam and radiationradiation

=> Tolerance for rms phase shake 10 degrees per module=> Tolerance for rms phase shake 10 degrees per module

=> Equivalent tolerance for rms electron beam straightness 2 => Equivalent tolerance for rms electron beam straightness 2 m m

Preserve transverse overlap between beam and Preserve transverse overlap between beam and radiationradiation => Tolerance for betatron amplitude < 8 => Tolerance for betatron amplitude < 8 m (beam radius m (beam radius

dep.)dep.)

Avoid longitudinal phase slippage between beam and Avoid longitudinal phase slippage between beam and radiationradiation

=> Tolerance for rms phase shake 10 degrees per module=> Tolerance for rms phase shake 10 degrees per module

=> Equivalent tolerance for rms electron beam straightness 2 => Equivalent tolerance for rms electron beam straightness 2 m m




Beam Based Alignment Tolerances (Paul Emma)Beam Based Alignment Tolerances (Paul Emma)

0.040.04

44

100100

100100

22




Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.5 mmPeriod Length 3.0 cmEffective On-Axis Field 1.296 TK 3.630

Module Length 3.40 mNumber of Modules 33Undulator Magnet Length 112.2 m

Break Length 49.6 - 49.6 - 72.3 cmTotal Device Length 130.4 m

Lattice Type FODOMagnet Type permanentNominal Magnet Length 5 cmQF Gradient 60 T/mQD Gradient -60 T/mAverage Function at 1.5 Å (14.09 GeV) 30 mAverage Function at 15. Å (4.46 GeV) 8.9 mLowest Usable Energy 1.84 GeV

Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.5 mmPeriod Length 3.0 cmEffective On-Axis Field 1.296 TK 3.630

Module Length 3.40 mNumber of Modules 33Undulator Magnet Length 112.2 m

Break Length 49.6 - 49.6 - 72.3 cmTotal Device Length 130.4 m

Lattice Type FODOMagnet Type permanentNominal Magnet Length 5 cmQF Gradient 60 T/mQD Gradient -60 T/mAverage Function at 1.5 Å (14.09 GeV) 30 mAverage Function at 15. Å (4.46 GeV) 8.9 mLowest Usable Energy 1.84 GeV

Summary of Nominal Undulator ParametersSummary of Nominal Undulator Parameters




LCLS Operating Points for 1 nC Bunch Charge (New)LCLS Operating Points for 1 nC Bunch Charge (New)

LCLS Operating Point at LCLS Operating Point at 1.5 Å1.5 ÅLCLS Operating Point at LCLS Operating Point at 1.5 Å1.5 Å

Operating PointOperating Point Operating PointOperating Point




LCLS Operating Points for 1 nC Bunch Charge (New)LCLS Operating Points for 1 nC Bunch Charge (New)

LCLS Operating Point at LCLS Operating Point at 15 Å15 ÅLCLS Operating Point at LCLS Operating Point at 15 Å15 Å

Operating PointOperating PointOperating PointOperating Point




Vacuum Chamber WakefieldsVacuum Chamber Wakefields

Predicted LCLS Current ProfilePredicted LCLS Current Profile

b=2.5 mmb=2.5 mmcopper surfacecopper surfacels=20 microns, hrms=100 nmls=20 microns, hrms=100 nmg_eff=12.3 mm, l_module=3.5 mg_eff=12.3 mm, l_module=3.5 m

Energy ChangeEnergy Change

rmsrms

meanmean




Relative Wakefield ContributionsRelative Wakefield Contributions

keV/m mean rms mean rms b=2.5 mm

RS -167.403 221.8906 100.0% 100.0% copper surface

GS -8.3186 18.5874 5.0% 8.4% ls=50 microns, hrms=100 nm

SM 0.0000 0.0000 0.0% 0.0% ls=50 microns, hrms=100 nm

GO -17.9418 6.2529 10.7% 2.8% g_eff=12.3 mm, Lmodule=3.5 m

Total -193.664 226.6923 115.7% 102.2%

keV/m mean rms mean rms b=2.5 mm

RS -167.403 221.8906 100.0% 100.0% copper surface

GS -32.6213 77.733 19.5% 35.0% ls=20 microns, hrms=100 nm

SM -0.1846 0.5117 0.1% 0.2% ls=20 microns, hrms=100 nm

GO -17.9418 6.2529 10.7% 2.8% g_eff=12.3 mm, Lmodule=3.5 m

Total -218.151 250.3583 130.3% 112.8%

ResistiveResistive

SurfaceSurfaceRoughnessRoughness

GeometricGeometric

ResistiveResistive

SurfaceSurfaceRoughnessRoughness

GeometricGeometric




Longitudinal Aspect Ratios for Surface Roughness WakefieldsLongitudinal Aspect Ratios for Surface Roughness Wakefields

Aspect Ratio = Aspect Ratio =

Relative Contribution of Relative Contribution of Roughness Wakefield is Roughness Wakefield is small for Aspect Ratios > small for Aspect Ratios > 200200

Threshold for Noticeable Threshold for Noticeable Contribution is Describable Contribution is Describable by Aspect Ratioby Aspect Ratio

Aspect Ratio = Aspect Ratio =

Relative Contribution of Relative Contribution of Roughness Wakefield is Roughness Wakefield is small for Aspect Ratios > small for Aspect Ratios > 200200

Threshold for Noticeable Threshold for Noticeable Contribution is Describable Contribution is Describable by Aspect Ratioby Aspect Ratio

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500

Rougness Period [microns]

RM

S R

ou

gh

nes

s A

mp

litu

de

[nm

]

Aspect Ratio 500

0

100

200

300

400

500

600

700

800

0 100 200 300 400 500

Rougness Period [microns]

RM

S R

ou

gh

nes

s A

mp

litu

de

[nm

]

Aspect Ratio 500

0

200

400

600

800

1000

0 100 200 300 400 500 600 700 800 900 1000

Aspect Ratio

Mea

n a

nd

RM

S W

akef

ield

(s)

[kV

/m]

-mean

rms

fit

0

200

400

600

800

1000

0 100 200 300 400 500 600 700 800 900 1000

Aspect Ratio

Mea

n a

nd

RM

S W

akef

ield

(s)

[kV

/m]

-mean

rms

fit

rmsh

/2

Constant rmsConstant rms




Workshop on Undulator ParametersWorkshop on Undulator Parameters

LCLS Undulator Parameter WorkshopChaired by

Heinz-Dieter Nuhn (SLAC)

Dates

October 24, 2003

Location

APS, Argonne, USA

Workshop RecommendationsWorkshop Recommendations

•Set Undulator PeriodSet Undulator Period•Reduction of maximum available linac energyReduction of maximum available linac energy•Undulator gap height increaseUndulator gap height increase•Longer break distancesLonger break distances•Weaker FODO latticeWeaker FODO lattice




Undulator ReviewUndulator Review

LCLS Undulator Review

Chaired by

Kem Robinson (LBNL)

Dates

November 13, 2003

Location

APS, Argonne, USA

Review Recommendations related to K Review Recommendations related to K adjustmentsadjustments

•Canted Undulator Poles instead of Comb DeviceCanted Undulator Poles instead of Comb Device




Diagnostics and Commissioning WorkshopDiagnostics and Commissioning Workshop

LCLS Diagnostics and Commissioning WorkshopChaired by

Heinz-Dieter Nuhn (SLAC)

Dates

January 19-20, 2004

Location

UCLA, Los Angeles, USA

http://ssrl.slac.stanford.edu/lcls/undulator/meetings/2004-01-19_diagnostics_comissioning/

Workshop RecommendationsWorkshop Recommendations

• No X-Ray Diagnostics in break sectionsNo X-Ray Diagnostics in break sections• Use X-Ray Diagnostics Down Stream of UndulatorUse X-Ray Diagnostics Down Stream of Undulator• Use trajectory distortion method to characterize Use trajectory distortion method to characterize

FEL radiation vs. z. FEL radiation vs. z. • Investigate Use of Spontaneous Radiation to Investigate Use of Spontaneous Radiation to

Characterize Undulator PerformanceCharacterize Undulator Performance

• Commissioning StepsCommissioning Steps•Spontaneous Radiation CharacterizationSpontaneous Radiation Characterization•15 Angstrom FEL Characterization15 Angstrom FEL Characterization•Shorter Wavelength FEL CharacterizationShorter Wavelength FEL Characterization




Measurement of SASE Gain along the undulatorMeasurement of SASE Gain along the undulatorMeasurement of SASE Gain along the undulatorMeasurement of SASE Gain along the undulator

GENESIS Simulations by Z. HuangGENESIS Simulations by Z. HuangGENESIS Simulations by Z. HuangGENESIS Simulations by Z. Huang




Spontaneous vs. FEL RadiationSpontaneous vs. FEL Radiation -1--1-

Figure by S. ReicheFigure by S. ReicheFigure by S. ReicheFigure by S. Reiche




Spontaneous vs. FEL Radiation Spontaneous vs. FEL Radiation -2--2-





Spontaneous vs. FEL Radiation Spontaneous vs. FEL Radiation -3--3-





Baseline Parameter ChoicesBaseline Parameter ChoicesBaseline Parameter ChoicesBaseline Parameter Choices

Minimal Performance ConfigurationMinimal Performance ConfigurationCanted poles with fixed offset for setting K in the MMF only Canted poles with fixed offset for setting K in the MMF only BPMs and quads fixed to the undulator strongbackBPMs and quads fixed to the undulator strongbackNo remote K adjustmentNo remote K adjustmentNo roll away undulatorsNo roll away undulators5 degrees of freedom remote motion control for the Quadrupole-5 degrees of freedom remote motion control for the Quadrupole-Undulator-BPM unitUndulator-BPM unitHorizontal gapHorizontal gapPermanent magnet quadrupolesPermanent magnet quadrupolesHydrostatic Leveling System (HLS), Wire position monitor (WPS)Hydrostatic Leveling System (HLS), Wire position monitor (WPS)

Possible enhancement (design revisions)Possible enhancement (design revisions)Remotely controlled K adjustment, preferably without requiring Remotely controlled K adjustment, preferably without requiring undulator motion.undulator motion.Roll-away capabilityRoll-away capabilityElectromagnetic quads or coils on permanent magnet quads to Electromagnetic quads or coils on permanent magnet quads to measure the beam position relative to the quadrupole centermeasure the beam position relative to the quadrupole center

Minimal Performance ConfigurationMinimal Performance ConfigurationCanted poles with fixed offset for setting K in the MMF only Canted poles with fixed offset for setting K in the MMF only BPMs and quads fixed to the undulator strongbackBPMs and quads fixed to the undulator strongbackNo remote K adjustmentNo remote K adjustmentNo roll away undulatorsNo roll away undulators5 degrees of freedom remote motion control for the Quadrupole-5 degrees of freedom remote motion control for the Quadrupole-Undulator-BPM unitUndulator-BPM unitHorizontal gapHorizontal gapPermanent magnet quadrupolesPermanent magnet quadrupolesHydrostatic Leveling System (HLS), Wire position monitor (WPS)Hydrostatic Leveling System (HLS), Wire position monitor (WPS)

Possible enhancement (design revisions)Possible enhancement (design revisions)Remotely controlled K adjustment, preferably without requiring Remotely controlled K adjustment, preferably without requiring undulator motion.undulator motion.Roll-away capabilityRoll-away capabilityElectromagnetic quads or coils on permanent magnet quads to Electromagnetic quads or coils on permanent magnet quads to measure the beam position relative to the quadrupole centermeasure the beam position relative to the quadrupole center




ConclusionsConclusions

Requirements for LCLS undulator are well Requirements for LCLS undulator are well establishedestablished

LCLS undulator performance requirements are well LCLS undulator performance requirements are well understoodunderstood

Risks have been assessed and undulator Risks have been assessed and undulator specifications address the riskspecifications address the risk

Small parameter adjustments are being made asSmall parameter adjustments are being made asthe undulator design goes into greater detail and the undulator design goes into greater detail and commissioning procedures are being worked out.commissioning procedures are being worked out.

Requirements for LCLS undulator are well Requirements for LCLS undulator are well establishedestablished

LCLS undulator performance requirements are well LCLS undulator performance requirements are well understoodunderstood

Risks have been assessed and undulator Risks have been assessed and undulator specifications address the riskspecifications address the risk

Small parameter adjustments are being made asSmall parameter adjustments are being made asthe undulator design goes into greater detail and the undulator design goes into greater detail and commissioning procedures are being worked out.commissioning procedures are being worked out.




End of Presentation

Documents

Physics Performance Details [email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator Center