Transcript Physics Performance Details

Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
March 3, 2004
Undulator Overview
FEL Performance Assessment
Recent Undulator Parameter Changes
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Linac Coherent Light Source
Undulator
Near Hall
Far Hall
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
LCLS Undulator Schematic (Regular Section)
3,400
496
723 mm
UNDULATOR
11,915 mm
Weak Horizontal Steering Coil
Total Lattice Length 131,120 mm
Weak Vertical Steering Coil
Total Device Length 130,397 mm
Beam Position Monitor
Wire/OTR Region
Quadrupoles
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Undulator Performance Requirements
Parameter
Symbol
Target
(Nom.)
Effective Undulator Parameter
K
3.630
Average Gap Height
g
6.5
mm
Average Period Length
lu
30.00
mm
Wiggle Plane
Units
Tolerance
(critical)
±0.015 %
horizontal
±0.03
—
Trajectory Straightness Tolerance
Dx
2
mm
—
Segment Phase Slippage Tolerance
Df
10
degrees
—
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Tolerance Analysis: RON
R. Dejus, N. Vinokurov
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Trajectory Straightness Requirement
Preserve transverse overlap between beam and
radiation
=> Tolerance for betatron amplitude < 8 mm (beam radius dep.)
Avoid longitudinal phase slippage between beam and
radiation
=> Tolerance for rms phase shake 10 degrees per module
=> Equivalent tolerance for rms electron beam straightness 2 mm
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Beam Based Alignment Tolerances (Paul Emma)
description
value
unit
BPM rms resolution
1
mm
BPM offsets (uncorrelated)
50
mm 100
BPM offsets (correlated)
300
mm
rms BPM ‘random-walk’ over length of undulator
BPM mean calibration error
10
%
mean calibration error of all BPMs
BPM rms calibration spread
3
%
rms calibration error spread over BPMs
quad. offsets (uncorrelated)
50
mm 100
quad. offsets (correlated)
300
mm
rms quad ‘random-walk’ over length of undulator
quad. mean gradient error
0 .3
%
mean gradient error of all quadrupoles
quad rms gradient error spread
0 .3
%
rms gradient error spread over quadrupoles
undulator rms pole field errors
0.04
0 .1
%
rms pole field errors spread
mover mean calibration error
5
%
mean calibration error of all magnet movers
mover rms calibration spread
3
%
rms calibration error spread over magnet movers
mover reproducibility (backlash)
1
mm
incoming mean trajectory error
10

initial constant launch error in units of rms beam size
incoming rms trajectory jitter
0 -0 . 1

initial variable launch error in units of rms beam size
rms energy measurement error
2
%
uncertainty in knowledge of beam energy
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
comments
2
4
net resolution  not necessarily single pulse
rms BPM-to-BPM survey and electrical offsets
rms quad-to-quad survey errors
backlash  mover attains setting to within 1 mm
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Summary of Nominal Undulator Parameters
Undulator Type
Magnet Material
Wiggle Plane
Gap
Period Length
Effective On-Axis Field
K
planar hybrid
NdFeB
horizontal
6.5
3.0
1.296
3.630
Module Length
Number of Modules
Undulator Magnet Length
3.40
33
112.2
m
Break Length
Total Device Length
49.6 - 49.6 - 72.3
130.4
cm
m
Lattice Type
Magnet Type
Nominal Magnet Length
QF Gradient
QD Gradient
Average b Function at 1.5 Å (14.09 GeV)
Average b Function at 15. Å (4.46 GeV)
Lowest Usable Energy
FODO
permanent
5
60
-60
30
8.9
1.84
cm
T/m
T/m
m
m
GeV
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
mm
cm
T
m
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
LCLS Operating Points for 1 nC Bunch Charge (New)
Operating Point
Operating Point
LCLS Operating Point at 1.5 Å
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
LCLS Operating Points for 1 nC Bunch Charge (New)
Operating Point
Operating Point
LCLS Operating Point at 15 Å
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Vacuum Chamber Wakefields
b=2.5 mm
copper surface
ls=20 microns, hrms=100 nm
g_eff=12.3 mm, l_module=3.5 m
Predicted LCLS Current Profile
mean
rms
Energy Change
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Relative Wakefield Contributions
keV/m
mean
rms
mean
rms
b=2.5 mm
copper surface
RS
-167.403
221.8906
100.0%
100.0%
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
copper surface
RS
-167.403
221.8906
100.0%
100.0%
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%
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Resistive
Surface
Roughness
Geometric
Resistive
Surface
Roughness
Geometric
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Linac Coherent Light Source
Longitudinal Aspect Ratios for Surface Roughness Wakefields
Aspect Ratio
2 / 
= hrms
Mean and RMS Wakefield (s) [kV/m]
1000
800
600
-mean
rms
fit
400
200
0
0
100
200
300
400
500
600
700
800
900
1000
Aspect Ratio
RMS Roughness Amplitude [nm]
Relative Contribution of
Roughness Wakefield is small
for Aspect Ratios > 200
Threshold for Noticeable
Contribution is Describable by
Aspect Ratio
800
700
Aspect Ratio 500
600
500
400
300
Constant rms
200
100
0
0
100
200
300
Rougness Period [microns]
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
400
500
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Workshop on Undulator Parameters
LCLS Undulator Parameter Workshop
Chaired by
Heinz-Dieter Nuhn (SLAC)
Dates
October 24, 2003
Location
APS, Argonne, USA
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Workshop Recommendations
•Set Undulator Period
•Reduction of maximum available linac energy
•Undulator gap height increase
•Longer break distances
•Weaker FODO lattice
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Undulator Review
LCLS Undulator Review
Chaired by
Kem Robinson (LBNL)
Dates
Review Recommendations related to K
adjustments
•Canted Undulator Poles instead of Comb Device
November 13, 2003
Location
APS, Argonne, USA
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Diagnostics and Commissioning Workshop
LCLS Diagnostics and Commissioning Workshop
Chaired by
Heinz-Dieter Nuhn (SLAC)
Dates
January 19-20, 2004
Location
UCLA, Los Angeles, USA
Workshop Recommendations
• No X-Ray Diagnostics in break sections
• Use X-Ray Diagnostics Down Stream of Undulator
• Use trajectory distortion method to characterize
FEL radiation vs. z.
• Investigate Use of Spontaneous Radiation to
Characterize Undulator Performance
• Commissioning Steps
•Spontaneous Radiation Characterization
•15 Angstrom FEL Characterization
•Shorter Wavelength FEL Characterization
http://ssrl.slac.stanford.edu/lcls/undulator/meetings/2004-01-19_diagnostics_comissioning/
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Measurement of SASE Gain along the undulator
GENESIS Simulations by Z. Huang
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Spontaneous vs. FEL Radiation
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
-1-
Figure by S. Reiche
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Spontaneous vs. FEL Radiation
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
-2-
Figure by S. Reiche
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Spontaneous vs. FEL Radiation
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
-3-
Figure by S. Reiche
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Baseline Parameter Choices
Minimal Performance Configuration
Canted poles with fixed offset for setting K in the MMF only
BPMs and quads fixed to the undulator strongback
No remote K adjustment
No roll away undulators
5 degrees of freedom remote motion control for the QuadrupoleUndulator-BPM unit
Horizontal gap
Permanent magnet quadrupoles
Hydrostatic Leveling System (HLS), Wire position monitor (WPS)
Possible enhancement (design revisions)
Remotely controlled K adjustment, preferably without requiring
undulator motion.
Roll-away capability
Electromagnetic quads or coils on permanent magnet quads to
measure the beam position relative to the quadrupole center
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
Conclusions
Requirements for LCLS undulator are well established
LCLS undulator performance requirements are well
understood
Risks have been assessed and undulator specifications
address the risk
Small parameter adjustments are being made as
the undulator design goes into greater detail and
commissioning procedures are being worked out.
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]
Linac Coherent Light Source
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
End of Presentation
Undulator Systems Review, March 3 - 4, 2004
Physics Performance Details
Heinz-Dieter Nuhn, SLAC / SSRL
[email protected]