P. Emma FAC Meeting 27 Oct Physics Update P. Emma FAC Meeting October 27, 2005 LCLS

P. Emma FAC Meeting 27 Oct No New Physics Surprises 1999:Surface roughness wakefield 2001:CSR micro-bunching instability 2002:Space-charge enhanced micro- bunching instability 2004:AC resistive-wall undulator wake 2005:no new set-backs? We must be too busy with construction? Thanks for past help from: K. Bane, Z. Huang, G. Stupakov, and Saldin, Schneidmiller, Yurkov

P. Emma FAC Meeting 27 Oct Normal Incidence Laser on Cathode laser beam e  beam Advantages No lossy, pulse distorting gratingNo lossy, pulse distorting grating Non-dispersed beam – less $Non-dispersed beam – less $ Mirror change without gun ventMirror change without gun vent Optics allows continuous variation of cathode beam sizeOptics allows continuous variation of cathode beam sizeDisadvantages Mirror wakefield (solved)Mirror wakefield (solved) Mirror requires space (solved)Mirror requires space (solved)Advantages No lossy, pulse distorting gratingNo lossy, pulse distorting grating Non-dispersed beam – less $Non-dispersed beam – less $ Mirror change without gun ventMirror change without gun vent Optics allows continuous variation of cathode beam sizeOptics allows continuous variation of cathode beam sizeDisadvantages Mirror wakefield (solved)Mirror wakefield (solved) Mirror requires space (solved)Mirror requires space (solved) Dowell, Gilevich, Limborg, White previous grazing incidence

P. Emma FAC Meeting 27 Oct Electron Trajectory Jitter sensitivity tolerance Form budget with a few discreet tolerance levels, opening challenging tolerances but holding tight on more standard ones Total amplitude 2 for N uncorrelated kicks, <10% Trajectory amplitude w.r.t. beam size

P. Emma FAC Meeting 27 Oct Trajectory Stability – Sources of Jitter (f > 10 Hz) Steering coil current regulation (120 x, 121 y ) Bend magnet trim coil current reg. (13 x & 2 y ) Misaligned quads/sol’s + current reg. (148 mag’s) Quad/solenoid mech. vibration (148 mag’s) CSR kicks with bunch length jitter (BC2, x only) Transverse wakes and charge jitter (X-band RF) Drive laser pointing stability Expected Sources of Transverse Jitter

P. Emma FAC Meeting 27 Oct Steering coils ( ppM  6% of beam size ) Trim coils ( ppM  2% ) Misaligned quads (  200  m: ppM  6% ) Quad/solenoid vibration (  m required  10% ) CSR kicks ( 1 nC,  z /  z  10%:  ~20%, x-only ) Wakes (  200  m,  /  2%  2% ) Drive laser pointing (  ~1% ) Trajectory Stability – Tol’s & Expectations System Stability Requirements at f > 10 Hz 0.2 nC is more stable

P. Emma FAC Meeting 27 Oct Quadrupole Magnet Vibration rubber boot on water pump R. Stege, J. Turner, 1994 R. Stege, J. Turner, 1994 Existing Linac ‘QE’ Quadrupole Magnets 12 quads need rms  500 nm (most new injector quads) 101 magnets need rms  100 nm (existing linac quads) 35 quads need rms  50 nm (mostly new LTU quads)

P. Emma FAC Meeting 27 Oct CSR-Induced x -Trajectory Jitter  10% bunch length jitter   16% ‘core’ trajectory jitter 22  m 20  m 18  m 1-nC core

P. Emma FAC Meeting 27 Oct Trajectory Feedback at Undulator Start undulator starts at Z = 0 5-  m BPM resolution of final 10 BPMs gives centroid stabilization to 5% of rms beam size at: f < 10 Hz (120 Hz rate)

P. Emma FAC Meeting 27 Oct Quad. Power Supply Regulation (Long-Term)  < 0.02 over all random quadrupole errors  k/k  = 1% to 0.01% rms over 24 hrs+ |k/k||k/k||k/k||k/k|

P. Emma FAC Meeting 27 Oct Magnet Polarities/Labeling Defined MMF will measure magnets and clearly label polarities

P. Emma FAC Meeting 27 Oct Commissioning – Tune-up ‘Stoppers’ SLAC linac tunnel research yard BC1 BC2 undulator 6 MeV 135 MeV 4.3 GeV 13.6 GeV …linac L0 rfgun L3L1 X L2 Jan. through July ’ MeV   abort Full set of beam diagnostics at each tune-up point TCAV0 TCAV3

P. Emma FAC Meeting 27 Oct Commissioning Plans for each System

P. Emma FAC Meeting 27 Oct LCLS Feedback Performance (use CSR  P/P ) at undulator entrance J. Wu  I pk /I pk0 (%) feedback on feedback off

P. Emma FAC Meeting 27 Oct CSR as Relative Bunch Length Monitor J. Wu Red curve: Gaussian Black curve: Uniform Red dots: ‘Real’ CSR detector is critical to LCLS stability (UCLA)

P. Emma FAC Meeting 27 Oct Relaxed Undulator Tolerances Full undulator error budget   0.5°C   1°F (H.-D. Nuhn) Beam-Finder Wire (BFW) to locate upstream end (D. Walters) Alignment drift tolerances loosened Correction strategy with target time-scales (FAC suggestion)

P. Emma FAC Meeting 27 Oct After beam-based alignment Undulator Alignment Drift – Long Term (24 hrs)  10  m quad and BPM drift MICADO steering applied Tolerance set at  5  m alignment drift over 24 hrs

P. Emma FAC Meeting 27 Oct Kem’s Correction Zones* Zone 1 (non-invasive correction) 120-Hz traj-feedback (LTU BPM’s)120-Hz traj-feedback (LTU BPM’s) 0.1-Hz traj-feedback (und. BPM’s)0.1-Hz traj-feedback (und. BPM’s) Zone 2 (  t > 1 hr,  P/P 0  > 90%, non-invasive) MICADO steering within undulatorMICADO steering within undulator Zone 3 (  t > 24 hr,  P/P 0  > 75%, invasive) Weighted steering of undulator traj. (1 min.)Weighted steering of undulator traj. (1 min.)... or quadrupole gradient scans - fast BBA (10 min.)... or quadrupole gradient scans - fast BBA (10 min.) Possible x-ray pointing (few min.)Possible x-ray pointing (few min.) Zone 4 (  t > 1 wk,  P/P 0  1 wk,  P/P 0  < 50%, machine time) One iteration of BBA (<1 hr)One iteration of BBA (<1 hr) Zone 5 (  t > 6 mo, shut-down) Tunnel survey with all movers set to zero (1 wk)Tunnel survey with all movers set to zero (1 wk) Full 3 iterations of BBA (~3 hrs)Full 3 iterations of BBA (~3 hrs) *FAC suggestion, April ‘05

P. Emma FAC Meeting 27 Oct Å with Optical Klystron Enhancement Yuantao Ding, Zhirong Huang K = 2.7 E = 13.6 GeV  = 1.2  m I pk = 3.4 kA  = 30 m  E /E = 0.005% 4 “OK” chicanes (long breaks) Laser-Heater   /2  -bunching issue? Shim gap   g = 2 mm SASE sim. ~longer L sat Future?

P. Emma FAC Meeting 27 Oct Summary Normal incidence simplifies drive laser (Gilevich) Trajectory stability expectations: 24% x & 14% y Quadrupole current regulation specified Magnet polarities defined Commissioning plans formed Feedback systems require CSR monitor (UCLA) Relaxed undulator tolerances (Milton, Nuhn) 1-Å future operation with “OK”? Electron beam commissioning through BC1 starts Dec. ’06 !