Download ppt - Introduction Heinz-Dieter Nuhn, SLAC / LCLS November 14, 2005

1Introduction – November 14, 2005 Heinz-Dieter Nuhn, SLAC / LCLSBeam Based Undulator Measurements Workshop [email protected]

IntroductionHeinz-Dieter Nuhn, SLAC / LCLS

November 14, 2005

IntroductionHeinz-Dieter Nuhn, SLAC / LCLS

November 14, 2005

Need for Beam Based Undulator K Measurements

Review of Beam Based K Measurement Discussions

LCLS Undulator Diagnostics Baseline Components

LCLS FEL Commissioning Milestones

Workshop Objective and Agenda

Charge to the Workshop

Need for Beam Based Undulator K Measurements

Review of Beam Based K Measurement Discussions

LCLS Undulator Diagnostics Baseline Components


Workshop Objective and Agenda

Charge to the Workshop


Linac Coherent Light Source

Near Hall

Far Hall

Undulator



Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.8 mmPeriod Length 30.0 ± 0.05 mmEffective On-Axis Field 1.249 TStandard Effective K 3.500 ± 0.015%Range of Effective Undulator Parameter K 3.500 - 3.493 (3.480)Accumulated Segment Phase Error Tolerance 10 degrees

(at any point along segment)

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

Standard Break Lengths 48.2 - 48.2 - 94.9 cmNominal Total Device Length 130.954 m

Quadrupole Magnet Technology EMQNominal Quadrupole Magnet Length 7 cmIntegrated Quadrupole Gradient 3.0 T

Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.8 mmPeriod Length 30.0 ± 0.05 mmEffective On-Axis Field 1.249 TStandard Effective K 3.500 ± 0.015%Range of Effective Undulator Parameter K 3.500 - 3.493 (3.480)Accumulated Segment Phase Error Tolerance 10 degrees

(at any point along segment)

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

Standard Break Lengths 48.2 - 48.2 - 94.9 cmNominal Total Device Length 130.954 m

Quadrupole Magnet Technology EMQNominal Quadrupole Magnet Length 7 cmIntegrated Quadrupole Gradient 3.0 T

Summary of Nominal Undulator Parameters


Undulator Segment PrototypeUndulator Segment Prototype


Undulator Pole Canting

• Canting comes from wedged spacers

• 4.5 mrad cant angle• 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


Using Undulator Roll-Away and K Adjustment Function

Neutral; K=3.5000; x=+0.0 mm

SpontTp; K=3.4929; x=+3.0 mm RollAway; K=0.0000; x=+100 mm

PowerTp; K=3.4804; x=+8.5 mm

Horizontal position of undulator segment can be remotely controlled correct Keff on beam axis

This adjustment range goes from fraction of a percent to a complete field turn-off.

Horizontal position of undulator segment can be remotely controlled correct Keff on beam axis

This adjustment range goes from fraction of a percent to a complete field turn-off.

Beam AxisBeam Axis


Measurement of Spontaneous Radiation Using RolloutMeasurement of Spontaneous Radiation Using Rollout

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


Effects Influencing Keff

Undulator Segment Tuning

Undulator Temperature

Transverse Segment Position

Segment Fiducialization and Alignment

Electron Beam Trajectory

Environmental Field in Undulator Hall

Radiation Damage

Effects Influencing Keff

Undulator Segment Tuning

Undulator Temperature

Transverse Segment Position

Segment Fiducialization and Alignment

Electron Beam Trajectory

Environmental Field in Undulator Hall

Radiation Damage

Insufficient Knowledge of Actual K Seen by Electrons N

eed fo

r Beam

Based

Un

du

lator K

Measu

remen

ts

See Tolerance Budget on next Slide


Segment Detuning Sub-Budget

MMF K KK K T x

2

2

ii i

KK p

p

Parameter pi Typical Value rms dev. pi Note

KMMF 3.5 0.0003 ±0.015 % uniform

K -0.0019 °C-1 0.0001 °C-1 Thermal Coefficient

T 0 °C 0.32 °C ±0.56 °C uniform without compensation

K 0.0023 mm-1 0.00004 mm-1 Canting Coefficient

x 1.5 mm 0.05 mm Horizontal Positioning

2 2 2 2 2

MMF K K K KK K T T x x

/ 0.020%K K


January 2004 Z. Huang

Sven Reiche

September 2004: LCLS Diagnostics and Commissioning WorkshopHigh-Resolution Effective K Measurements Using Spontaneous Undulator Radiation , Bingxin Yang http://www-ssrl.slac.stanford.edu/lcls/workshops/2004-09-22_diag_comm/bxyang_CommWorkshop200409.ppt

October 2004: LCLS WeekUndulator / FEL Diagnostics, Bingxin Yang https://www-ssrl.slac.stanford.edu/lcls/fac/talks_oct2004/Yang_FAC200410.ppt

January 2005: LCLS FEL Physics MeetingSimulation Results for 200-pC ("chargito") SASE performance with AC Wake, Jim Welch http://www-ssrl.slac.stanford.edu/lcls/internals/felphysics/2005-01-18/k_meas_talk.ppt

April 2005 ICFA Commissioning Workshop at Zeuthen (Work Package 6)Measurement of Undulator Segment K_effective using Spontaneous Radiation in the Near Hall of the LCLS, Jim Welch http://adweb.desy.de/mpy/ICFA2005_Commissioning/Talks(PDF)/April%2021%20(Thursday)/WP6_1/Welch_Undulator%20Commissioning.pdf

High resolution undulator measurements using angle-integrated spontaneous spectra, Bingxin Yang http://adweb.desy.de/mpy/ICFA2005_Commissioning/Talks(PDF)/April%2021%20(Thursday)/WP6_2/Yang_High%20Resolution%20Undulator%20measurements.pdf

July 2005 LCLS Week:K-Measurement Strategies discussion presented by Jim Welch and Bingxin Yang

October 2005 FAC MeetingX-Ray Diagnostic, Richard Bionta http://ssrl.slac.stanford.edu/lcls/fac/talks_oct_2005/bionta_xtod_diagnostics_fac.ppt

January 2004 Z. Huang

Sven Reiche

September 2004: LCLS Diagnostics and Commissioning WorkshopHigh-Resolution Effective K Measurements Using Spontaneous Undulator Radiation , Bingxin Yang http://www-ssrl.slac.stanford.edu/lcls/workshops/2004-09-22_diag_comm/bxyang_CommWorkshop200409.ppt

October 2004: LCLS WeekUndulator / FEL Diagnostics, Bingxin Yang https://www-ssrl.slac.stanford.edu/lcls/fac/talks_oct2004/Yang_FAC200410.ppt

January 2005: LCLS FEL Physics MeetingSimulation Results for 200-pC ("chargito") SASE performance with AC Wake, Jim Welch http://www-ssrl.slac.stanford.edu/lcls/internals/felphysics/2005-01-18/k_meas_talk.ppt

April 2005 ICFA Commissioning Workshop at Zeuthen (Work Package 6)Measurement of Undulator Segment K_effective using Spontaneous Radiation in the Near Hall of the LCLS, Jim Welch http://adweb.desy.de/mpy/ICFA2005_Commissioning/Talks(PDF)/April%2021%20(Thursday)/WP6_1/Welch_Undulator%20Commissioning.pdf

High resolution undulator measurements using angle-integrated spontaneous spectra, Bingxin Yang http://adweb.desy.de/mpy/ICFA2005_Commissioning/Talks(PDF)/April%2021%20(Thursday)/WP6_2/Yang_High%20Resolution%20Undulator%20measurements.pdf

July 2005 LCLS Week:K-Measurement Strategies discussion presented by Jim Welch and Bingxin Yang

October 2005 FAC MeetingX-Ray Diagnostic, Richard Bionta http://ssrl.slac.stanford.edu/lcls/fac/talks_oct_2005/bionta_xtod_diagnostics_fac.ppt

Discussions of Beam Based K Measurements Based on Spontaneous Undulator Radiation


Diagnostics presently being developed to Characterize Electron Beam and X-Ray Properties include

Electron Beam Diagnostics in the Linac-To-Undulator (LTU) Beamline

Electron Beam and X-Ray Diagnostics in the Undulator

Electron Beam Diagnostics after the Undulator (Dump Line)

X-Ray Diagnostics in the Front End Enclosure (FEE)

Diagnostics presently being developed to Characterize Electron Beam and X-Ray Properties include

Electron Beam Diagnostics in the Linac-To-Undulator (LTU) Beamline

Electron Beam and X-Ray Diagnostics in the Undulator

Electron Beam Diagnostics after the Undulator (Dump Line)

X-Ray Diagnostics in the Front End Enclosure (FEE)

Review of Existing LCLS Baseline Diagnostics


Control of Electron Beam Properties before Entrance into the UndulatorControl of Electron Beam Properties before Entrance into the Undulator

LTU Electron Beam Diagnostics


4 wires 4 wires , , , , (+ collimators)(+ collimators)

1 OTR 1 OTR slice- slice-, , , , abort dumpabort dump

OTR OTR slice E-spread (0.02%) slice E-spread (0.02%)

xx11 xx22

2 BPMs 2 BPMs energy jitterenergy jitter

relative energy relative energy centroid resolution: centroid resolution:

0.003%0.003% (5- (5-m BPMs)m BPMs)

LTULTU

Courtesy of Paul EmmaCourtesy of Paul Emma


Control of Electron Beam Trajectory inside the UndulatorControl of Electron Beam Trajectory inside the Undulator

X-Ray Beam Diagnostics


Short Break Section Components

Courtesy of Dean WaltersCourtesy of Dean Walters

QuadrupoleQuadrupole

Undulator SegmentUndulator Segment

Cherenkov DetectorCherenkov Detector


RF Cavity BPMRF Cavity BPM

Beam Finder WireBeam Finder Wire


Long Break Section Components

QuadrupoleQuadrupole


Cherenkov DetectorCherenkov Detector


Diagnostics TankDiagnostics Tank

Beam Finder WireBeam Finder Wire

RF Cavity BPMRF Cavity BPM

Courtesy of Dean WaltersCourtesy of Dean Walters


Electron Beam Diagnostics after UndulatorElectron Beam Diagnostics after Undulator

After Undulator Electron Beam Diagnostics


1 OTR 1 OTR energy-spread (0.001%) energy-spread (0.001%)

1 BPM 1 BPM energy-jitter (0.003%) energy-jitter (0.003%)

Dump-LineDump-Line

Courtesy of Paul EmmaCourtesy of Paul Emma


Measurement of X-Ray Beam Properties in FEEMeasurement of X-Ray Beam Properties in FEE

Diagnostics in the Front End Enclosure


FEE Layout

Fastclosevalve

Slit

Ion Chamber

Ion Chamber

Diagnostics Package

Gas Attenuator

SolidAttenuator

SiC Mirror 1

Be Mirrors 2 & 3

SiC Mirror 2

Collimator 1

DiagnosticsPackage

Courtesy of Richard BiontaCourtesy of Richard Bionta


Desired Spontaneous Measurements

f(x,y,1) Spatial distribution around 1

1 1st harmonic Photon wavelength

1st harmonic wavelength spread

Beam direction

u Total energy / pulse

u,1 Temporal variation in beam parameters

,x y



FEE Cartoon

SolidAttenuator

Gas Attenuator

High-EnergySlit

Start of Experimental

Hutches

5 mm diameter

collimators

Muon Shield

FEL Offset mirror

system

TotalEnergy

CalorimeterWFOV Direct

Imager

Spectrometer / Indirect Imager mirror

Windowless Ion

Chamber

Windowless Ion

Chamber

e-

Diagnostic Package

Spectrometer camera



Redundant Commissioning Instrumentation

Instrument Purpose Adjustment Calibration and Physics risks

Direct Imager SP f(x,y), look for FEL, measure FEL u, f(x,y), x,y

ND filter, Attenuators

Scintillator linearity, Attenuator linearity and background

Indirect Imager Measure FEL u, f(x,y), spectral imaging of SP and FEL harmonics, attenuator calibration

Mirror Angle Mirror reflectivity, damage

Total Energy FEL u Attenuators Energy to Heat, damage

Ion Chamber FEL u, x,y,x',y' Pressure Signal strength

Spectrometers FEL, SP spectra Attenuators Resolution, damage



MS3BO_040: Front End Beneficial Occupancy (9/5/2007)

MS3BO_030: Undulator Facility Beneficial Occupancy (12/3/2007)

MS3_XT040: Solid Attenuator Installation Complete (12/14/2007)

MS3_XT045: Gas Attenuator Installation Complete (12/14/2007)

MS3_XT080: Start Front End Enclosure Commissioning (3/4/2008)

MS3_LN015: Start Linac-to-Undulator (LTU) Commissioning (5/12/2008)

MS3_XT066: Start Near Experimental Hall Checkout (6/12/2008)

MS3_UN020: Undulator System Installation Complete (7/18/2008)

MS3_UN025: Start Undulator Commissioning (1st Light) (7/24/2008)

MS3BO_040: Front End Beneficial Occupancy (9/5/2007)

MS3BO_030: Undulator Facility Beneficial Occupancy (12/3/2007)

MS3_XT040: Solid Attenuator Installation Complete (12/14/2007)

MS3_XT045: Gas Attenuator Installation Complete (12/14/2007)

MS3_XT080: Start Front End Enclosure Commissioning (3/4/2008)

MS3_LN015: Start Linac-to-Undulator (LTU) Commissioning (5/12/2008)

MS3_XT066: Start Near Experimental Hall Checkout (6/12/2008)

MS3_UN020: Undulator System Installation Complete (7/18/2008)

MS3_UN025: Start Undulator Commissioning (1st Light) (7/24/2008)


Diagnostics needed around July 2008Diagnostics needed around July 2008


Define a strategy for using spontaneous undulator radiation to measure the K value of every individual LCLS Undulator Segment after installation in the Undulator Hall.

To reach the objective, the physics and technologies necessary need to be identified. Workshop discussions will include

Usable spectral features of spontaneous radiation

Strategies for beam-based K measurements

Specifications for suitable instruments

Scheduling issues

Three Work Packages have been defined and assigned to three different groups. Work described by these Work Packages has been carried out in preparation of the workshop and will be presented and discussed at the workshop.

Define a strategy for using spontaneous undulator radiation to measure the K value of every individual LCLS Undulator Segment after installation in the Undulator Hall.

To reach the objective, the physics and technologies necessary need to be identified. Workshop discussions will include

Usable spectral features of spontaneous radiation

Strategies for beam-based K measurements

Specifications for suitable instruments

Scheduling issues

Three Work Packages have been defined and assigned to three different groups. Work described by these Work Packages has been carried out in preparation of the workshop and will be presented and discussed at the workshop.

Workshop Objective


Workshop Agenda


Group: B. Yang, R. Dejus

Task: Examine robustness of angle-integrated measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the high-energy edge of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement (limited by beam-pipe apertures, or apertures at the measuring point) should be considered.

Group: B. Yang, R. Dejus

Task: Examine robustness of angle-integrated measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the high-energy edge of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement (limited by beam-pipe apertures, or apertures at the measuring point) should be considered.

Work Package 1: Angle Integrated Measurement


Group: J. Welch, R. Bionta, S. Reiche

Task: Examine robustness of pinhole measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of pinhole and spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator, as seen through a small angular aperture, to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement should be determined, and the effects of misalignment of the aperture or undulator axis should be carefully considered.

Group: J. Welch, R. Bionta, S. Reiche

Task: Examine robustness of pinhole measurements of undulator spectrum. Consider effects of errors in beam alignment, undulator magnet structure, straightness of vacuum pipe, alignment of pinhole and spectrometer, etc. Consider effects of location of undulator segment being tested. Determine what are realistic values for the precision with which the value of K can be determined for an undulator segment at the beginning, middle, and end of the undulator.

This task explores the use of the fundamental spectral peak (the third harmonic may also be considered) of a single undulator, as seen through a small angular aperture, to measure its K parameter. The measuring spectrometer will be located in the LCLS FEE, roughly 100 m downstream from the final undulator segment. Realistic values for the angular acceptance of the measurement should be determined, and the effects of misalignment of the aperture or undulator axis should be carefully considered.

Work Package 2: Pinhole Measurement


Group: J. Hastings, et al.

Task: Assume that a single shot spectral measurement is needed for an LCLS spontaneous undulator pulse. What are the best options for doing the measurement? What spectral resolution can be obtained using these methods? What are the effects of beam jitter, spectrometer misalignment, etc?

This task explores the design and performance of x-ray spectrometers capable of providing centroid or edge position with high resolution, on a single-shot of radiation from a single LCLS undulator. The spectrometer will most likely be located in the LCLS FEE, about 100 m downstream from the final undulator segment.

Group: J. Hastings, et al.

Task: Assume that a single shot spectral measurement is needed for an LCLS spontaneous undulator pulse. What are the best options for doing the measurement? What spectral resolution can be obtained using these methods? What are the effects of beam jitter, spectrometer misalignment, etc?

This task explores the design and performance of x-ray spectrometers capable of providing centroid or edge position with high resolution, on a single-shot of radiation from a single LCLS undulator. The spectrometer will most likely be located in the LCLS FEE, about 100 m downstream from the final undulator segment.

Work Package 3: Single-Shot Spectral Measurement


Characterize the spectral features of spontaneous synchrotron radiation that are usable for beam-based K-measurements.

Identify the most appropriate strategy for beam-based K-measurements.

Specify suitable instruments for the identified beam-based K-measurement strategy.

List expected performance parameters such as resolution of K measurement as function of beam charge, and segment location as well as expected tolerances to trajectory and energy jitter.

List any open questions regarding the feasibility of the most appropriate strategy.

List the R&D activities, if any, needed before the design of a measurement system can be completed and manufacturing/procurement can start.

Characterize the spectral features of spontaneous synchrotron radiation that are usable for beam-based K-measurements.

Identify the most appropriate strategy for beam-based K-measurements.

Specify suitable instruments for the identified beam-based K-measurement strategy.

List expected performance parameters such as resolution of K measurement as function of beam charge, and segment location as well as expected tolerances to trajectory and energy jitter.

List any open questions regarding the feasibility of the most appropriate strategy.

List the R&D activities, if any, needed before the design of a measurement system can be completed and manufacturing/procurement can start.

Workshop Charge


End of Presentation