Undulator Bench Requirements Zack Wolf SLAC October 14
Undulator Bench Requirements Zack Wolf SLAC October 14, 2004 Undulator Bench Requirements 1 Zack Wolf wolf@slac. stanford. edu
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. October 14, 2004 Undulator Bench Requirements 2 Zack Wolf wolf@slac. stanford. edu
Measurement System Overview October 14, 2004 Undulator Bench Requirements 3 Zack Wolf wolf@slac. stanford. edu
Example Of A Bench Stages, Probes ANL Bench Carriage Air Bearing (Vacuum Load) Bench Drive Horizontal Reference Surface Vertical Reference Surface Photo courtesy of R. Ruland October 14, 2004 Undulator Bench Requirements 4 Zack Wolf wolf@slac. stanford. edu
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. October 14, 2004 Undulator Bench Requirements 5 Zack Wolf wolf@slac. stanford. edu
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 October 14, 2004 Undulator Bench Requirements 6 Zack Wolf wolf@slac. stanford. edu
Bench Length Wire System Phase Matching Specify: 8 m bench October 14, 2004 Undulator Bench Requirements 7 Zack Wolf wolf@slac. stanford. edu
Bench Shape DESY Bench Carriage is captured. October 14, 2004 Undulator Bench Requirements 8 Zack Wolf wolf@slac. stanford. edu
Quality of Bench Construction § Probe position affects the measurement results. § Bench errors affect the probe position. v. We must specify the bench errors so the measurements are within tolerance. October 14, 2004 Undulator Bench Requirements 9 Zack Wolf wolf@slac. stanford. edu
Plan to Specify Bench Error Limits Bench Error Probe Motion Error Measurement Error Calculated Undulator Parameter Error Undulator Error After Tuning October 14, 2004 Undulator Bench Requirements 10 Zack Wolf wolf@slac. stanford. edu
Undulator Requirements* Parameter Value Units mm Max trajectory walkoff per 10 m 5 Max first field integral Max second field integral Electron phase deviation RMS magnet error DB/B 40 50 10 0. 015 m. Tm 2 degrees % *From the LCLS parameters database on the web. October 14, 2004 Undulator Bench Requirements 11 Zack Wolf wolf@slac. stanford. edu
Measurement Result Error Limits Parameter Value Calc trajectory walkoff in undulator 2 Units mm Calc trajectory slope at exit 8. 80 x 10 -7 Calc trajectory offset at exit 1. 10 x 10 -6 m Calc phase deviation 10 deg Field measurement accuracy 0. 015 % October 14, 2004 Undulator Bench Requirements 12 Zack Wolf wolf@slac. stanford. edu
Probe Motion Errors Probe motion errors cause measurement errors which cause errors in calculated undulator parameters Actual path Ideal path Need limits on dx, dy, dz, and dp October 14, 2004 Undulator Bench Requirements 13 Zack Wolf wolf@slac. stanford. edu
Vertical Probe Motion By(y, z) = B 0 cosh(2 py/lu) sin(2 pz/lu) By Vertical probe motion error limit set by field measurement accuracy (LCLS-TN-04 -8): By DB Dy y For DB/B 0 < 0. 015 %, Dy < 83 mm Take Dymax = 20 mm (Agrees with fiducialization requirement of 20 μm. ) October 14, 2004 Undulator Bench Requirements 14 Zack Wolf wolf@slac. stanford. edu
Horizontal Probe Motion DB/B 0 = -(0. 77 1/m) Dx Horizontal probe motion error limit set by field measurement accuracy (LCLS-TN-04 -8): By For DB/B 0 < 0. 015 %, DB Dx Dx < 195 mm x Take Dxmax = 40 mm (Agrees with fiducialization requirement of 40 μm. ) October 14, 2004 Undulator Bench Requirements 15 Zack Wolf wolf@slac. stanford. edu
Axial Probe Motion Calculated trajectory offset error places limit Dzmax = 5. 9 mm Take Dzmax = 3 mm (LCLS-TN-04 -8) October 14, 2004 Undulator Bench Requirements (Don’t use entire error budget on one error. ) 16 Zack Wolf wolf@slac. stanford. edu
Summary of Probe Motion Requirements Parameter Value Units Maximum vertical deviation Dy 20 mm Maximum horizontal deviation Dx 40 mm Maximum axial deviation Dz 3 mm Maximum probe angle error 8 mrad (see LCLS-TN-04 -8 for details) October 14, 2004 Undulator Bench Requirements 17 Zack Wolf wolf@slac. stanford. edu
Bench Errors Cause Probe Motion X Deviation (Δx) Y Deviation (Δy) Pitch Deviation (Δy, Δz) October 14, 2004 Undulator Bench Requirements Roll Deviation (Δy) Yaw Deviation (Δz) 18 Zack Wolf wolf@slac. stanford. edu
Summary of Bench Construction Requirements Parameter Probe Motion Dx Carriage x deviation Dy Carriage y deviation Dy Carriage roll deviation Carriage pitch deviation Dy, Dz Carriage yaw deviation Dz October 14, 2004 Undulator Bench Requirements 19 Quad Limit 40 14 14 4. 2 Zack Wolf wolf@slac. stanford. edu Units mm mm mrad
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 mm Carriage y deviation 14 mm Carriage roll deviation 14 mrad Carriage pitch deviation 4. 2 mrad Carriage yaw deviation 4. 2 mrad 3) Limit switches, brakes, bench non-magnetic, … (see LCLS-TN-04 -8 for complete list) October 14, 2004 Undulator Bench Requirements 20 Zack Wolf wolf@slac. stanford. edu
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