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Undulator Bench Requirements

Undulator Bench Requirements. Zack Wolf SLAC. 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.

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Undulator Bench Requirements

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  1. Undulator Bench Requirements Zack Wolf SLAC

  2. 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.

  3. Measurement System Overview

  4. 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

  5. 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.

  6. 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

  7. Bench Length Wire System Phase Matching Specify: 8 m bench

  8. Bench Shape DESY Bench Carriage is captured.

  9. 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.

  10. Plan to Specify Bench Error Limits Bench Error Probe Motion Error Measurement Error Calculated Undulator Parameter Error Undulator Error After Tuning

  11. Undulator Requirements* Max trajectory walkoff per 10 m: 5 mm Max first field integral: 40 mTmMax second field integral: 50 mTm2 Electron phase deviation: 10 degrees RMS magnet error DB/B: 0.015 % *From the LCLS parameters database on the web.

  12. Measurement Result Error Limits

  13. 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

  14. Vertical Probe Motion By By(y, z) = B0 cosh(2py/lu) sin(2pz/lu) Vertical probe motion error limit set by field measurement accuracy (LCLS-TN-04-8): By For DB/B0 < 0.015 %, DB Dy < 83 mm y Dy Take Dymax = 20 mm (Agrees with fiducialization requirement of 20 μm.)

  15. Horizontal Probe Motion DB/B0 = -(0.77 1/m) Dx Horizontal probe motion error limit set by field measurement accuracy (LCLS-TN-04-8): By For DB/B0 < 0.015 %, DB Dx < 195 mm x Dx Take Dxmax = 40 mm (Agrees with fiducialization requirement of 40 μm.)

  16. Axial Probe Motion Calculated trajectory offset error places limit Dzmax = 5.9 mm Take Dzmax = 3 mm (LCLS-TN-04-8) (Don’t use entire error budget on one error.)

  17. Summary of Probe Motion Requirements (see LCLS-TN-04-8 for details)

  18. Bench Errors Cause Probe Motion X Deviation (Δx) Y Deviation (Δy) Roll Deviation (Δy) Pitch Deviation (Δy, Δz) Yaw Deviation (Δz)

  19. Summary of Bench Construction Requirements

  20. Conclusion We request from the vendor 1) An 8 meter long bench, 7 meters of travel 2) Carriage motion with the following specifications 3) Limit switches, brakes, bench non-magnetic, … (see LCLS-TN-04-8 for complete list)

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