Undulator / FEL Commissioning Plans Heinz-Dieter Nuhn, SLAC / SSRL September 22, 2004

Undulator Commissioning September 22, 2004 Heinz-Dieter Nuhn, SLAC / SSRLLCLS Commissioning Workshop [email protected]@slac.stanford.edu

Undulator / FEL Commissioning PlansHeinz-Dieter Nuhn, SLAC / SSRL

September 22, 2004

Undulator / FEL Commissioning PlansHeinz-Dieter Nuhn, SLAC / SSRL

September 22, 2004

FY2004 Undulator Parameter Changes

Summary of January Undulator Commissioning Workshop

Undulator Commissioning Issues

FEL Characterization

FY2004 Undulator Parameter Changes

Summary of January Undulator Commissioning Workshop

Undulator Commissioning Issues

FEL Characterization


Linac Coherent Light Source

Near Hall

Far Hall

Undulator



FEL Design Changes Since the May 2003 Lehman ReviewFEL Design Changes Since the May 2003 Lehman Review

Canting of Undulator Poles

Remote Undulator Roll-Away and K Adjustment Function

Increase in Undulator Gap

Reduction in Maximum Beam Energy

Reduction in Quadrupole Gradient

Increase in Beta Function

Increase in Break Section Length

Electromagnetic Quadruples

Canting of Undulator Poles

Remote Undulator Roll-Away and K Adjustment Function

Increase in Undulator Gap

Reduction in Maximum Beam Energy

Reduction in Quadrupole Gradient

Increase in Beta Function

Increase in Break Section Length

Electromagnetic Quadruples


New: Undulator Pole Canting

•Canting comes from wedged spacers•4.5 mrad cant•Gap can be adjusted by lateral displacement of wedges•1 mm shift means 4.5 microns in gap, or 8.2 Gauss •Beff adjusted to desired value

Courtesy of Liz MoogCourtesy of Liz Moog

Suggested by J. Pflueger, DESY


Undulator Roll-Away and K Adjustment FunctionUndulator Roll-Away and K Adjustment Function

Neutral; K=3.4965; x=+0.0 mm First; K=3.5000; x=-1.5 mm

Last; K=3.4929; x=+1.5 mm RollAway; K=0.0000; x=+100 mm

PowerTp; K=3.4804; x=+7.0 mm


Effective B field vs. xEffective B field vs. x

Measured slope of 6.6 Gauss/mm agrees with calculations(~ 5.7 Gauss/mm for 3 mrad cant)

Field variation allowance between segments is B/B = 1.5x10-4, or B = 2 Gauss, which translates to x = 0.3 mm ( or 1 micron in gap)



Canting the poles helps in many ways

Facilitates final setting of Beff

Remote control of position allows run-time adjustment

Allows compensating for temperature effect on field strength: ±1.0°C temperature error would require ±1.2 mm lateral shift of undulator



RMS phase error at different x positionsRMS phase error at different x positions

No significant dependence on X

An RMS phase error of ~ 6.5 degree is an upper limit for near-perfect (~100%) performance



Period-averaged horizontal trajectories at 14.1 GeVPeriod-averaged horizontal trajectories at 14.1 GeV

Trajectories are all well behaved and well within the 2 m tolerance for maximum walk-off from a straight line

(X in mm)



May 2003 August 2004

Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.0 6.8 mmGap Canting Angle 0.0 4.5 mradPeriod Length 30.0 ± 0.1 mmEffective On-Axis Field 1.325 1.249 TEffective Undulator Parameter K 3.630 ± 0.015% 3.500 ± 0.015%

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

Standard Break Lengths 18.7 - 18.7 - 42.1 48.2 - 48.2 - 94.9 cmTotal Device Length 121.0 131.9 m

Lattice Type FODOIntegrated QF Gradient 5.355 3.000 T/mIntegrated QD Gradient -5.295 -3.000 T/mAverage Function at 1.5 Å 18 30 mAverage Function at 15. Å 7.3 8.9 m

May 2003 August 2004

Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.0 6.8 mmGap Canting Angle 0.0 4.5 mradPeriod Length 30.0 ± 0.1 mmEffective On-Axis Field 1.325 1.249 TEffective Undulator Parameter K 3.630 ± 0.015% 3.500 ± 0.015%

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

Standard Break Lengths 18.7 - 18.7 - 42.1 48.2 - 48.2 - 94.9 cmTotal Device Length 121.0 131.9 m

Lattice Type FODOIntegrated QF Gradient 5.355 3.000 T/mIntegrated QD Gradient -5.295 -3.000 T/mAverage Function at 1.5 Å 18 30 mAverage Function at 15. Å 7.3 8.9 m

Amplitudes of FEL Parameter ChangesAmplitudes of FEL Parameter Changes


May 2003 August 2004 Change

Electron Beam Energy 14.35 13.64 GeV -5.0 %Emittance 0.043 0.045 nm rad +5.2 %Avg. Electron Beam Radius 27 35 µm +27.5 %Avg. Electron Beam Divergence 1.6 1.3 µrad -17.5 %Peak Beam Power 49 46 TW -5.0 %FEL Parameter (3D) 0.00033 0.00032 -3.5 %Power Gain Length (3D) 4.2 4.3 m +3.6 %Saturation Length (w/o Breaks) 82 86 m +4.9 %Saturation Length (w/ Breaks) 89 101 m +13.5 %Peak Saturation Power 7.4 7.6 GW +2.5 %*Coherent Photons per Pulse 1.4×1012 1.5×1012 +2.5 %*Peak Brightness 1.5×1033 1.5×1033 ** +2.5 %*Average Brightness 4.6×1022 4.7×1022 ** +2.5 %*Peak Spont. Power per Pulse 91 73 GW -19.7 %

*Increase due to 3D effects (reduction in diffraction due to beam radius increase)** [Ph./s/mm2/mr2/.1%]

May 2003 August 2004 Change

Electron Beam Energy 14.35 13.64 GeV -5.0 %Emittance 0.043 0.045 nm rad +5.2 %Avg. Electron Beam Radius 27 35 µm +27.5 %Avg. Electron Beam Divergence 1.6 1.3 µrad -17.5 %Peak Beam Power 49 46 TW -5.0 %FEL Parameter (3D) 0.00033 0.00032 -3.5 %Power Gain Length (3D) 4.2 4.3 m +3.6 %Saturation Length (w/o Breaks) 82 86 m +4.9 %Saturation Length (w/ Breaks) 89 101 m +13.5 %Peak Saturation Power 7.4 7.6 GW +2.5 %*Coherent Photons per Pulse 1.4×1012 1.5×1012 +2.5 %*Peak Brightness 1.5×1033 1.5×1033 ** +2.5 %*Average Brightness 4.6×1022 4.7×1022 ** +2.5 %*Peak Spont. Power per Pulse 91 73 GW -19.7 %

*Increase due to 3D effects (reduction in diffraction due to beam radius increase)** [Ph./s/mm2/mr2/.1%]

Performance Impact of Changes (1.5 Å)Performance Impact of Changes (1.5 Å)


Undulator / FEL Commissioning DocumentsUndulator / FEL Commissioning Documents

“Report of the LCLS Diagnostics and Commissioning Workshop”SLAC-R-715, LCLS-TN-04-02http://www-ssrl.slac.stanford.edu/lcls/technotes/LCLS-TN-04-2.pdf

LCLS PRD1.1-002 “LCLS Start-Up Test Plan”http://www-ssrl.slac.stanford.edu/lcls/prd/1.1-002-r0.pdf


Undulator Diagnostics and Commissioning Undulator Diagnostics and Commissioning Workshop 1/19-20/04Workshop 1/19-20/04

Scope

Commissioning of the FEL Undulator with Beam

GoalsEnd-Of-Construction Goal

Defined by DOE to close-off construction project (CD-4)

One of the first Commissioning Milestones

Commissioning Goal

Get LCLS ready for operation

PrerequisitesUndulator, Diagnostics, Shielding, Beam Dump etc. in Place

Commissioning Without Beam for all Components Complete

Main Commissioning TasksCharacterization of Electron Beam Up-Stream of Undulator

Establishment of a Good Beam Trajectory Through Undulator to Beam-Dump

Characterization of Spontaneous Radiation

Establishment of SASE Gain

Characterization of FEL Radiation

Scope

Commissioning of the FEL Undulator with Beam

GoalsEnd-Of-Construction Goal

Defined by DOE to close-off construction project (CD-4)

One of the first Commissioning Milestones

Commissioning Goal

Get LCLS ready for operation

PrerequisitesUndulator, Diagnostics, Shielding, Beam Dump etc. in Place

Commissioning Without Beam for all Components Complete

Main Commissioning TasksCharacterization of Electron Beam Up-Stream of Undulator

Establishment of a Good Beam Trajectory Through Undulator to Beam-Dump

Characterization of Spontaneous Radiation

Establishment of SASE Gain

Characterization of FEL Radiation

Low ChargeSingle Shot

Low ChargeSingle Shot

Low Charge, 10 HzLow Charge, 10 Hz

10 Hz10 Hz


January 2004 Workshop RecommendationsJanuary 2004 Workshop Recommendations

No Intra-Undulator-Segment X-Ray Diagnostics in Baseline Design

Instead: End-of-Undulator X-Ray Diagnostics to Characterize FEL Radiation vs. z

Trajectory Distortion Method

Roll-Away Undulator Segments Function

Investigation of Spontaneous Radiation as Diagnostics Tools

Code Development to Support Commissioning

Areas for Follow-Up R&D

Study of Spectral and Spatial Distribution of Spontaneous Radiation

Diagnostics Prototyping

Microbunching Measurement

No Intra-Undulator-Segment X-Ray Diagnostics in Baseline Design

Instead: End-of-Undulator X-Ray Diagnostics to Characterize FEL Radiation vs. z

Trajectory Distortion Method

Roll-Away Undulator Segments Function

Investigation of Spontaneous Radiation as Diagnostics Tools

Code Development to Support Commissioning

Areas for Follow-Up R&D

Study of Spectral and Spatial Distribution of Spontaneous Radiation

Diagnostics Prototyping

Microbunching Measurement


Commissioning PhasesCommissioning Phases

Phase 0: Beam Through Undulator (at 0.2 nC, sngl shot)

Phase I: Spontaneous Radiation (at 0.2 nC, 10 Hz)

Parameters: Energy 4.31-13.64 GeV, Emittance: not critical

Goals: Establish straight and stable trajectory, measure spontaneous radiation

Phase II a: Low Energy FEL Radiation (at 0.2-1 nC, 10 Hz)

Parameters: Energy: 4.31 GeV, Emittance: < 4 micronsPeak Current : < 1 kA

Goals: Characterize FEL radiation. Achieve saturation.

Phase II b: High Energy FEL Radiation (at 0.2-1 nC, 10 Hz)

Parameters: Energy: >4.31 -13.64 GeV, Emittance: 1.2- 4 micronsPeak Current : 1-3.4 kA

Goals: Characterize FEL radiation, gain. Achieve saturation.

Phase III: Transition to Operation (at 0.2-1 nC, 120 Hz)

Parameters: Energy: >4.45 -13.64 GeV, Emittance: 1.2- 4 micronsPeak Current : 1-3.4 kA

Goals: Bring FEL performance up to full operating performance levels.


LTU / Undulator Commissioning IssuesLTU / Undulator Commissioning Issues

Undulator Radiation Protection

Collimators

Tune-Up Dump

Roll-Away Undulators

Radiation Interlocks

Measurements of FEL Radiation vs. Z

Radiation Power Damage to Inter Undulator X-Ray Diagnostics

End-of-Undulator Diagnostics

Beam Based Detection of Gain Reducing Errors

Using Spontaneous Radiation

Using FEL Gain Curve

Numerical Simulation Support for Detector Development and Commissioning

Undulator Radiation Protection

Collimators

Tune-Up Dump

Roll-Away Undulators

Radiation Interlocks

Measurements of FEL Radiation vs. Z

Radiation Power Damage to Inter Undulator X-Ray Diagnostics

End-of-Undulator Diagnostics

Beam Based Detection of Gain Reducing Errors

Using Spontaneous Radiation

Using FEL Gain Curve

Numerical Simulation Support for Detector Development and Commissioning

See next talk by Sven Reiche !See next talk by Sven Reiche !


/2/2 /2/2

xx11 xx22 xx33

phase-1phase-1 phase-2phase-2 phase-1 phase-1 againagain

halohalo

ee beam beam

3 mm mm

2 mm2 mm

Two-Phase, Two-Plane Collimation, 1½ TimesTwo-Phase, Two-Plane Collimation, 1½ Times

undulator undulator beam beam pipepipe

2.5 mm5 mmedge edge scatteringscattering

(also collimation in (also collimation in yy and energy – see next slides) and energy – see next slides)

Undulator Radiation ProtectionUndulator Radiation Protection

Courtesy of Paul EmmaCourtesy of Paul Emma


EE11 EE

22

xx11yy11 xx22

yy22xx33yy33

LCLS Collimation Proposal (2 energy, 3 LCLS Collimation Proposal (2 energy, 3 xx, and 3 , and 3 yy adjustable collimators) adjustable collimators)muon muon

shieldingshielding

undulatorundulator

xx33 & & yy33

optional?optional?

Courtesy of Paul EmmaCourtesy of Paul Emma


22ndnd-order -order tracking with all tracking with all collimators collimators closed and big closed and big halohalo

2.5 mm2.5 mm

2-phase, 2-plane, and energy collimation in 22-phase, 2-plane, and energy collimation in 2ndnd-order-order

well well shadowed in shadowed in xx, , yy, and , and EE

?-CY3

-?CX32.0-CY2

-2.0CX22.0-CY1

-2.0CX1-5.0CE2

-5.0CE1

ymm

xmmColl.

xx,,yy = 4000 = 4000 m,m,

EE//EE = 10% (uniform) = 10% (uniform)

Courtesy of Paul Emma



GG = 110 T/m = 110 T/mTrack 100 times with:Track 100 times with:

DL2 BPM rms res. = 10 DL2 BPM rms res. = 10 mmDL2 BPM rms misa. = 200 DL2 BPM rms misa. = 200 mmDL2 Quad rms misa. = 200 DL2 Quad rms misa. = 200 mmUndulator Quad rms misa. = 100 Undulator Quad rms misa. = 100 mm

Correct und-launch, then open stopper-2 for one beam shot…Correct und-launch, then open stopper-2 for one beam shot…

Just Just 11 of 10011 of 100 trajectories exceed trajectories exceed 2.5 mm within undulator2.5 mm within undulatorNoneNone exceed exceed 3.5 mm3.5 mm

First beam shot First beam shot through undulator?through undulator?




Desirable measurements as function of position along undulator :

Intensity (LG, Saturation)

Spectral Distribution

Bunching

Total energy

Pulse length

Photon energy spectra

Spatial coherence

Spatial shape and centroid

Divergence

Desirable measurements as function of position along undulator :

Intensity (LG, Saturation)

Spectral Distribution

Bunching

Total energy

Pulse length


Spatial coherence


Divergence

FEL Gain MeasurementFEL Gain Measurement

Undulator RegimeUndulator Regime

Exponential Gain Regime

Exponential Gain Regime

Saturation

Saturation

1 % of X-Ray Pulse1 % of X-Ray Pulse

Electron BunchMicro-Bunching

Electron BunchMicro-Bunching


Quantities to be MeasuredQuantities to be Measured

Total energy

Pulse length


Spatial coherence


Divergence

Total energy

Pulse length


Spatial coherence


Divergence


Dose / Power ConsiderationsDose / Power Considerations

0.01

0.1

1

10

100

100 1000 10000

Photon energy (eV)

Flu

en

ce (

J/cm

^2

)

undulatorexitexperimentalhall A

experimentalhall B

C

Si

W

Au

Be

0.01

0.1

1

10

0.1 1 10 100

grazing angle (degrees)

energ

y d

ensit

y c

orr

ect

ion

0.8 keV critical angle

0.8 keV

8 keV critical angle

8 keV

with electroncorrection

no electroncorrection

Fluence to Melt

Energy Density Reduction of a

Reflector

Be will melt at normal incidence at E < 3 KeV near undulator exit.

Using Be as a grazing incidence reflector may gain x 10 in tolerance.

Courtesy of Richard BiontaCourtesy of Richard Bionta


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

Direct: Detectors in the Breaks between Undulator Segments. Fluence levels too large for x-ray!.

Alternative: End-Of-Undulator DiagnosticsTurn-Off Gain at Selectable Point Along Undulator by

Introduction of trajectory distortion

Removal of undulator segments (New roll-away option)

Characterize x-ray beam at single station down stream of undulator

Direct: Detectors in the Breaks between Undulator Segments. Fluence levels too large for x-ray!.

Alternative: End-Of-Undulator DiagnosticsTurn-Off Gain at Selectable Point Along Undulator by

Introduction of trajectory distortion

Removal of undulator segments (New roll-away option)

Characterize x-ray beam at single station down stream of undulator


Fastclosevalve

Slit A

PPS

13'Muonshield

Gas Attenuator

SolidAttenuator

Slit B

PPS

4'Muonshield

WindowlessIonChamber

Direct ImagerIndirect Imager

Spectrometer,Total Energy

PPS

AccessShaft

AccessShaft

Courtesy of Richard BiontaCourtesy of Richard Bionta


Measurement of SASE Gain withMeasurement of SASE Gain withTrajectory DistortionTrajectory Distortion

GENESIS Simulations by Z. Huang

Quadrupole Displacement at Selectable Point along Undulator

Quadrupole Displacement at Selectable Point along Undulator


Measurement of SASE Gain Using Rollaway OptionMeasurement of SASE Gain Using Rollaway Option

Undulator Segments can be removed by remote control from the end of the undulator. They will not effect radiation produced by earlier segments.


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

Figure by S. Reiche

See Thursday talk by Paul Emma

Weak FEL Signal Detection Using a Slowly Modulated Laser-Heater

See Thursday talk by Paul Emma

Weak FEL Signal Detection Using a Slowly Modulated Laser-Heater


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

Figure by S. Reiche


ConclusionsConclusions

Several Undulator Parameters have been Changed.New K Adjustment and Roll-Away Option will aid undulator and FEL commissioning.FEL and Spontaneous Radiation Diagnostics will be located after the end of the undulatorDetailed commissioning strategy is being developed. First Startup Test Plan exists.

PRD 1.1-002 LCLS Start-Up Test Plan (http://www-ssrl.slac.stanford.edu/lcls/prd/1.41002-r1.pdf)

Several Undulator Parameters have been Changed.New K Adjustment and Roll-Away Option will aid undulator and FEL commissioning.FEL and Spontaneous Radiation Diagnostics will be located after the end of the undulatorDetailed commissioning strategy is being developed. First Startup Test Plan exists.

PRD 1.1-002 LCLS Start-Up Test Plan (http://www-ssrl.slac.stanford.edu/lcls/prd/1.41002-r1.pdf)


End of Presentation