Physics Performance Details Heinz-Dieter Nuhn, SLAC / SSRL March 3, 2004 Undulator Overview FEL Performance Assessment Recent Undulator Parameter Changes Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Linac Coherent Light Source Undulator Near Hall Far Hall Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

LCLS Undulator Schematic (Regular Section) 3,400 496 723 mm UNDULATOR 11,915 mm Weak Horizontal Steering Coil Total Lattice Length 131,120 mm Weak Vertical Steering Coil Total Device Length 130,397 mm Beam Position Monitor Wire/OTR Region Quadrupoles Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Undulator Performance Requirements Parameter Symbol Target (Nom.) Units Tolerance (critical) Effective Undulator Parameter K 3.630 ±0.015 % Average Gap Height g 6.5 mm Average Period Length lu 30.00 ±0.03 Wiggle Plane horizontal — Trajectory Straightness Tolerance Dx 2 Segment Phase Slippage Tolerance Df 10 degrees Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Tolerance Analysis: RON R. Dejus, N. Vinokurov Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Beam Based Alignment Tolerances (Paul Emma) 2 100 100 0.04 4 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

LCLS Operating Points for 1 nC Bunch Charge (New) LCLS Operating Point at 1.5 Å Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

LCLS Operating Points for 1 nC Bunch Charge (New) LCLS Operating Point at 15 Å Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Vacuum Chamber Wakefields b=2.5 mm copper surface ls=20 microns, hrms=100 nm g_eff=12.3 mm, l_module=3.5 m Predicted LCLS Current Profile mean rms Energy Change Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Relative Wakefield Contributions keV/m mean rms   b=2.5 mm RS -167.403 221.8906 100.0% copper surface GS -8.3186 18.5874 5.0% 8.4% ls=50 microns, hrms=100 nm SM 0.0000 0.0% GO -17.9418 6.2529 10.7% 2.8% g_eff=12.3 mm, Lmodule=3.5 m Total -193.664 226.6923 115.7% 102.2% -32.6213 77.733 19.5% 35.0% ls=20 microns, hrms=100 nm -0.1846 0.5117 0.1% 0.2% -218.151 250.3583 130.3% 112.8% Resistive Surface Roughness Geometric Resistive Surface Roughness Geometric Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Longitudinal Aspect Ratios for Surface Roughness Wakefields Relative Contribution of Roughness Wakefield is small for Aspect Ratios > 200 Threshold for Noticeable Contribution is Describable by Aspect Ratio Constant rms Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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/ Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Measurement of SASE Gain along the undulator GENESIS Simulations by Z. Huang Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Spontaneous vs. FEL Radiation -1- Figure by S. Reiche Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Spontaneous vs. FEL Radiation -2- Figure by S. Reiche Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

Spontaneous vs. FEL Radiation -3- Figure by S. Reiche Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

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 as the undulator design goes into greater detail and commissioning procedures are being worked out. Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL

End of Presentation Undulator Systems Review, March 3 - 4, 2004 Heinz-Dieter Nuhn, SLAC / SSRL