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Zack Wolf
Undulator Bench Requirements
October 14, 20041
Undulator Bench Requirements
Zack Wolf
SLAC
Zack Wolf
Undulator Bench Requirements
October 14, 20042
Introduction
We require a measurement bench to move probes through the undulators.
To purchase the bench, we must determine specifications for it:
Physical characteristics such as the length must be determined.
The quality of the bench performance must be specified.
Zack Wolf
Undulator Bench Requirements
October 14, 20043
Measurement System Overview
Zack Wolf
Undulator Bench Requirements
October 14, 20044
Example Of A Bench
ANL Bench
Bench
Carriage
Drive
Air Bearing(Vacuum Load)
Stages, Probes
Photo courtesy of R. Ruland
Horizontal ReferenceSurface
Vertical ReferenceSurface
Zack Wolf
Undulator Bench Requirements
October 14, 20045
Tasks and Measurement Equipment Requirements
Straighten trajectory (Hall probe, coil) K vs x (Hall probe) Phase shimming (Hall probe) First and second field integrals (Hall probe, coil,
wire system) Phase matching (Hall probe, two undulators on
bench) Fiducialization (Add “pointed” magnets, bench flat)
Account for all equipment space requirements when specify length.
Zack Wolf
Undulator Bench Requirements
October 14, 20046
Bench Dimensions
Length, important Transverse dimensions, leave up to
manufacturer to meet probe motion tolerances, handling requirements, etc.
Shape, need carriage constrained so air bearing can not come free
Need to specify length and shape
Zack Wolf
Undulator Bench Requirements
October 14, 20047
Bench Length
WireSystem
PhaseMatching
Specify: 8 m bench
Zack Wolf
Undulator Bench Requirements
October 14, 20048
Bench Shape
Line a r M o to r
C a rria g e
Ha ll Pro b eX Y Sta g e
Ro ll Sta g e ,G o nio m e te r
G ra nite Ta b le
DESY Bench
Carriage is captured.
Zack Wolf
Undulator Bench Requirements
October 14, 20049
Quality of Bench Construction
Probe position affects the measurement results.
Bench errors affect the probe position.
We must specify the bench errors so the measurements are within tolerance.
Zack Wolf
Undulator Bench Requirements
October 14, 200410
Plan to Specify Bench Error Limits
Probe Motion Error
Bench Error
Measurement Error
Calculated Undulator Parameter Error
Undulator Error After Tuning
Zack Wolf
Undulator Bench Requirements
October 14, 200411
Undulator Requirements*
Parameter Value Units
Max trajectory walkoff per 10 m 5 mMax first field integral 40 Tm
Max second field integral 50 Tm2
Electron phase deviation 10 degrees
RMS magnet error B/B 0.015 %
*From the LCLS parameters database on the web.
Zack Wolf
Undulator Bench Requirements
October 14, 200412
Measurement Result Error Limits
Parameter Value Units
Calc trajectory walkoff in undulator 2 m
Calc trajectory slope at exit 8.80x10-7
Calc trajectory offset at exit 1.10x10-6 m
Calc phase deviation 10 deg
Field measurement accuracy 0.015 %
Zack Wolf
Undulator Bench Requirements
October 14, 200413
Probe Motion Errors
Need limits on dx, dy, dz, and dp
Ideal path
Actual path
Probe motion errors causemeasurement errors which causeerrors in calculated undulator parameters
Zack Wolf
Undulator Bench Requirements
October 14, 200414
Vertical Probe Motion
By By(y, z) = B0 cosh(2y/u) sin(2z/u)
y
By
B
y
For B/B0 < 0.015 %,
y < 83 m
Take ymax = 20 m
Vertical probe motion error limitset by field measurement accuracy
(LCLS-TN-04-8):
(Agrees with fiducialization requirement of 20 μm.)
Zack Wolf
Undulator Bench Requirements
October 14, 200415
Horizontal Probe Motion
x
By
B
x
B/B0 = -(0.77 1/m) x
For B/B0 < 0.015 %,
x < 195 m
Take xmax = 40 m
(Agrees with fiducialization requirement of 40 μm.)
Horizontal probe motion error limitset by field measurement accuracy
(LCLS-TN-04-8):
Zack Wolf
Undulator Bench Requirements
October 14, 200416
Axial Probe Motion
Calculated trajectory offset error places limit zmax = 5.9 m
Take zmax = 3 m
(LCLS-TN-04-8) (Don’t use entire error budget on one error.)
Zack Wolf
Undulator Bench Requirements
October 14, 200417
Summary of Probe Motion Requirements
Parameter Value Units
Maximum vertical deviation y 20 m
Maximum horizontal deviation x 40 m
Maximum axial deviation z 3 m
Maximum probe angle error 8 mrad
(see LCLS-TN-04-8 for details)
Zack Wolf
Undulator Bench Requirements
October 14, 200418
Bench Errors Cause Probe Motion
X Deviation (Δx) Y Deviation (Δy) Roll Deviation (Δy)
Pitch Deviation (Δy, Δz) Yaw Deviation (Δz)
Zack Wolf
Undulator Bench Requirements
October 14, 200419
Summary of Bench Construction Requirements
Parameter Probe
Motion
Quad
Limit
Units
Carriage x deviation x 40 mCarriage y deviation y 14 mCarriage roll deviation y 14 rad
Carriage pitch deviation y, z 4.2 rad
Carriage yaw deviation z 4.2 rad
Zack Wolf
Undulator Bench Requirements
October 14, 200420
Conclusion
We request from the vendor
1) An 8 meter long bench, 7 meters of travel
2) Carriage motion with the following specifications
Parameter Max Units
Carriage x deviation 40 m
Carriage y deviation 14 m
Carriage roll deviation 14 rad
Carriage pitch deviation 4.2 rad
Carriage yaw deviation 4.2 rad
3) Limit switches, brakes, bench non-magnetic, …(see LCLS-TN-04-8 for complete list)
