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LCLS Undulator Fiducialization

LCLS Undulator Fiducialization. by Yurii Levashov, SLAC. Outlook. LCLS Parameters Fiducialization Procedure Pointed Magnets PM Test Results Fiducialization Error Budget Summary. LCLS Parameters and Tolerances. 1.5 *10 -4. Fiducialization Procedure.

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LCLS Undulator Fiducialization

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  1. LCLS Undulator Fiducialization by Yurii Levashov, SLAC

  2. Outlook • LCLS Parameters • Fiducialization Procedure • Pointed Magnets • PM Test Results • Fiducialization Error Budget • Summary

  3. LCLS Parameters and Tolerances 1.5*10-4

  4. Fiducialization Procedure Goal to find position of undulator axis with respect to mechanical references. Based on results of magnetic measurements. Magnetic measurements and tuning should be done before fiducialization. Magnetic axis with respect to Hall probe sensitive area, i.e. magnetic reference. Coordinate transfer from magnetic to mechanical references. Pointed magnets as an intermediate reference.

  5. Fiducialization Procedure (cont.) X,Y,Z

  6. Fiducialization Procedure (cont.) • Alignment to the bench. Capacitor sensor measurements.. • Position of the axis • Hall probe scan in Y at different Z positions. Pitch correction. • Hall probe scan in Z at different Y. Effective K-value. • Hall probe centering w.r.t. PM center. Offset between undulator axis and PM. • Measurements at CMM. Offset between tooling balls.

  7. Pointed Magnet Fixture Pointed magnet misalignment? * I. Vasserman Quadrupole magnetic center definition using the hall probe measurement technique. APS-Pub. LS-285, Argonne, 2004

  8. Two-Point Measurement Algorithm By= 0

  9. Hall probe centering accuracy Starting from random positions (±0.2mm) from center, scan in X and Y. Differences in centering results w.r.t first scan shown. Std (in X)=3µm

  10. Pointed Magnet Calibration A1,2 = D/2 ± Δy Sentron 2-D XZM12 Hall probe Newport X-Y, model 406, stages with CMA-12CCCL actuators and ESP-300 controller

  11. Calibration Test Results • Do centering in one position • Rotate fixture at 180˚ • Do centering in second position • Calculate offset Calibration accuracy = 1µm in Y, 3µm in X

  12. Fiducialization Error Budget Total Fiducialization error includes the following components: • Finding undulator magnetic axis ~ 5µm • Hall probe centering ~ 1µm • Pointed magnet calibration ~ 3µm • Tooling ball eccentricity = 5µm • CMM measurement ~ 15µm • Other possible errors ~ ? (10µm) Total: 20 µm Alignment budget: sqrt(702 – 202) = 67µm

  13. Summary • Fiducialization procedure has been finalized. • Pointed magnet fixture has been developed, fabricated, and tested. • Adequate measurement algorithm has been proposed. • Fiducialization accuracy is expected to be ~ 20 µm.

  14. Acknowledgement Author would like to thank Z. Wolf (SLAC) and I. Vasserman (ANL) for ideas and fruitful discussions. Special thanks to D. Jensen (SLAC) and K. Hacker (DESY) who started the work on pointed magnets.

  15. End of presentation Thank you!

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