Linac/BC1 Commissioning P Linac/BC1 Commissioning P. Emma LCLS Injector Commissioning Workshop (ICW) Oct. 10, 2006 LCLS

LCLS Injector Commissioning Dates (’06 - ’07) July 24: Sector-20 ready for laser installation Aug. 29: Laser installation complete Dec. 18: Virtual cathode fully characterized (ready to install gun) Dec. 19: RF gun installation starts (10 days) + pre-beam checkout + laser rate switched to 30 Hz (5 days) Dec. 20-Jan. 1: Holidays Jan. 2: VVS’s switched on (RF power available) Jan. 12: First laser UV-light on cathode! Jan. 12-Feb. 4: Electrons in GTL and gun-spect. (RF processing L0a,b, L1, LX) Feb. 5: Beam into L0a, L0b and down to 135-MeV spect. Feb. 20: Beam into main linac (to TD11 dump) ~June: Take beam down full linac (to SL2 stopper)

Straight Ahead Spectrometer Bunch Length Diagnostics Injector Through BC1 RF Gun & Solenoid L0a&L0b S-Band Linacs Transverse RF Cavity BC1 (BPM, OTR, collimator) OTR & Wire Scanners Gun Spectrometer L1 S-Band Linac Wire Scanners + OTR Main SLAC Linac 135 MeV 250 MeV TD-11 stopper X-Band RF Straight Ahead Spectrometer Bunch Length Diagnostics 40 m

Dog-Leg-1 up to First L1 RF Section (135 MeV) Bend 2 Matching quads e- Bend 1 OTR Wire-scanner Existing linac Minimize energy spread

L1-Linac (135 to 250 MeV) Cut-off RF sections with new BPMs & quads inserted e- 21-1 klystron, new SS sub-booster Set RF phase (-25º) & voltage for BC1 compression

Accelerator Sections Straightened Coordinate Measurement Machine (CMM) after before (De/e  30%) Four RF sections measured on CMM and straightened (L0a, L0b, L1a, L1b) Jose Chan

Set S & X RF ampl. & phase, and chirp for BC1 compression BC1 Chicane e- tweaker quad 2 0-30 cm translation stage Bunch length monitors tweaker quad 1 OTR X-band RF collimator BPM Set S & X RF ampl. & phase, and chirp for BC1 compression

(allows passage of 30-GeV beam) Moveable BC1 Chicane BPM critical for energy feedback (20 mm resolution) offset: 0 to 30 cm (23 cm nominal) collimator BPM tweaker quadrupole screen (allows passage of 30-GeV beam) 3-cm contraction

BC1 Dipole Fields are Marginal tracking through fields measured with stretched wire De/e0  1 to 6 % Pole nose pieces in fabrication + tweaker quadrupoles available

Dispersion Correction in SPPS Chicane One linear comb. of 2 tweaker quads

Diagnostic Section After BC1 3 wire-scanners e- Bunch length monitors Insertable stopper (TD11) OTR Future EO? Measure emittance, beta match, bunch length, CSR effects

Tune-up simulations have been run... steering with quad and BPM offsets

Setup of Linac-1, X-band RF Phases 20-mm res. BC1 BPM 20-mm res. BC1 BPM LX RF phase L1 RF phase Linac-1 RF phase scan (X-band off, BC1 at 295 MeV) Linac-X RF phase scan (BC1 at 250 MeV) set phase to -25˚0.5˚ set phase to -160˚0.5˚ Linac-1 new rf gun 21-1b 21-1d X Set L1 and LX RF phase and amplitude Turn on BC1 energy feedback (if ready) Use RF-deflector to meas. bunch length (sz1) Adjust S-band RF phase (0.5˚) to set sz1  195 10 mm

Longitudinal Beam-Based Feedback gun L3 L2 X DL1 BC1 BC2 DL2 L1 sz1 d1 1 V1 sz2 d2 2 V2 d3 V3 d0 V0 Longitudinal feedback (J. Wu): Maintains DL1 energy, BC1 energy, post-BC1 bunch length Measures DL1-BPM, BC1-BPM, BC1 bunch-length monitor Controls L0 and L1 RF amplitude, and L1 RF phase Use MATLAB in 2007 as temporary slow (~1 Hz) solution

Slice-Emittance Measurement Simulation RF-deflector at 1 MV sy  bunch length slice OTR 10 times 135 MeV quad scanned

y-slice-Emittance Measurement in BC1 “Q21201” scanned ±20% 0.3 mm 16 mm

Full Compression (q = 5.70°) BC1 CSR Effects at 1 nC Nominal Bend (q = 4.97°) Full Compression (q = 5.70°) e/e0 = 1.04 e/e0 = 6.78 sz = 200 mm sz = 12 mm

R56 = 39 mm BC1 CSR Effects CSR-Track: De/e0  8%

Study Micro-bunching Instability at BC1 (~Summer 2007) Scan BC1 bend angle, , to adjust compression factor Use RF deflectors before and after BC1 to detect bunch density (energy) modulations and compare with micro-bunching gain from theory & simulations 0= 50 m 0= 150 m 0= 300 m  (degrees) Z. Huang

Concluding Remarks Drive-Laser and gun probably most intensive commissioning areas Linac through BC1 is mostly magnets, RF, and diagnostics (but most is new) Need to take beam down full linac (1 km) in order to use RF deflector (LOLA) in sector-29 (test BC1 compression) Next commissioning phase will start in ~Jan. ’08 with BC2, LTU, undulator, and dump