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Physics Performance Details Heinz-Dieter Nuhn, SLAC / SSRL March 3, 2004

Physics Performance Details Heinz-Dieter Nuhn, SLAC / SSRL March 3, 2004. Undulator Overview FEL Performance Assessment Recent Undulator Parameter Changes. Far Hall. Undulator. Near Hall. Linac Coherent Light Source. LCLS Undulator Schematic (Regular Section). 3,400. 496. 723 mm.

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Physics Performance Details Heinz-Dieter Nuhn, SLAC / SSRL March 3, 2004

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  1. Physics Performance DetailsHeinz-Dieter Nuhn, SLAC / SSRLMarch 3, 2004 • Undulator Overview • FEL Performance Assessment • Recent Undulator Parameter Changes Heinz-Dieter Nuhn, SLAC / SSRL

  2. Far Hall Undulator Near Hall Linac Coherent Light Source Heinz-Dieter Nuhn, SLAC / SSRL

  3. LCLS Undulator Schematic (Regular Section) 3,400 496 723 mm UNDULATOR 11,915 mm Weak Horizontal Steering Coil Total Lattice Length 131,120 mm Total Device Length 130,397 mm Weak Vertical Steering Coil Beam Position Monitor Wire/OTR Region Quadrupoles Heinz-Dieter Nuhn, SLAC / SSRL

  4. Undulator Performance Requirements Heinz-Dieter Nuhn, SLAC / SSRL

  5. Tolerance Analysis: RON R. Dejus, N. Vinokurov Heinz-Dieter Nuhn, SLAC / SSRL

  6. 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 Heinz-Dieter Nuhn, SLAC / SSRL

  7. Beam Based Alignment Tolerances (Paul Emma) 2 100 100 0.04 4 Heinz-Dieter Nuhn, SLAC / SSRL

  8. Summary of Nominal Undulator Parameters Undulator Type planar hybrid Magnet Material NdFeB Wiggle Plane horizontal Gap 6.5 mm Period Length 3.0 cm Effective On-Axis Field 1.296 T K 3.630 Module Length 3.40 m Number of Modules 33 Undulator Magnet Length 112.2 m Break Length 49.6 - 49.6 - 72.3 cm Total Device Length 130.4 m Lattice Type FODO Magnet Type permanent Nominal Magnet Length 5 cm QF Gradient 60 T/m QD Gradient -60 T/m Average b Function at 1.5 Å (14.09 GeV) 30 m Average b Function at 15. Å (4.46 GeV) 8.9 m Lowest Usable Energy 1.84 GeV Heinz-Dieter Nuhn, SLAC / SSRL

  9. LCLS Operating Points for 1 nC Bunch Charge (New) Operating Point Operating Point LCLS Operating Point at 1.5 Å Heinz-Dieter Nuhn, SLAC / SSRL

  10. LCLS Operating Points for 1 nC Bunch Charge (New) Operating Point Operating Point LCLS Operating Point at 15 Å Heinz-Dieter Nuhn, SLAC / SSRL

  11. Vacuum Chamber Wakefields b=2.5 mmcopper surfacels=20 microns, hrms=100 nm g_eff=12.3 mm, l_module=3.5 m Predicted LCLS Current Profile mean rms Energy Change Heinz-Dieter Nuhn, SLAC / SSRL

  12. Relative Wakefield Contributions Resistive SurfaceRoughness Geometric Resistive SurfaceRoughness Geometric Heinz-Dieter Nuhn, SLAC / SSRL

  13. Longitudinal Aspect Ratios for Surface Roughness Wakefields • Aspect Ratio = • Relative Contribution of Roughness Wakefield is small for Aspect Ratios > 200 • Threshold for Noticeable Contribution is Describable by Aspect Ratio Constant rms Heinz-Dieter Nuhn, SLAC / SSRL

  14. Workshop on Undulator Parameters LCLS Undulator Parameter Workshop Chaired by Heinz-Dieter Nuhn (SLAC) • Workshop Recommendations • Set Undulator Period • Reduction of maximum available linac energy • Undulator gap height increase • Longer break distances • Weaker FODO lattice Dates October 24, 2003 Location APS, Argonne, USA Heinz-Dieter Nuhn, SLAC / SSRL

  15. Undulator Review LCLS Undulator Review Chaired by • Review Recommendations related to K adjustments • Canted Undulator Poles instead of Comb Device Kem Robinson (LBNL) Dates November 13, 2003 Location APS, Argonne, USA Heinz-Dieter Nuhn, SLAC / SSRL

  16. Diagnostics and Commissioning Workshop LCLS Diagnostics and Commissioning Workshop • 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 Chaired by Heinz-Dieter Nuhn (SLAC) Dates January 19-20, 2004 Location UCLA, Los Angeles, USA http://ssrl.slac.stanford.edu/lcls/undulator/meetings/2004-01-19_diagnostics_comissioning/ Heinz-Dieter Nuhn, SLAC / SSRL

  17. Measurement of SASE Gain along the undulator GENESIS Simulations by Z. Huang Heinz-Dieter Nuhn, SLAC / SSRL

  18. Spontaneous vs. FEL Radiation -1- Figure by S. Reiche Heinz-Dieter Nuhn, SLAC / SSRL

  19. Spontaneous vs. FEL Radiation -2- Figure by S. Reiche Heinz-Dieter Nuhn, SLAC / SSRL

  20. Spontaneous vs. FEL Radiation -3- Figure by S. Reiche Heinz-Dieter Nuhn, SLAC / SSRL

  21. 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 Quadrupole-Undulator-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 Heinz-Dieter Nuhn, SLAC / SSRL

  22. 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 asthe undulator design goes into greater detail and commissioning procedures are being worked out. Heinz-Dieter Nuhn, SLAC / SSRL

  23. End of Presentation Heinz-Dieter Nuhn, SLAC / SSRL

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