1. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Linac Physics, Diagnostics, and Commissioning Strategy P. Emma LCLS FAC Meeting April 29, 2004 LCLS

2. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Nominal LCLS Linac Parameters for 1.5-Å FEL Single bunch, 1-nC charge, 1.2-  m slice emittance, 120-Hz repetition rate… (RF phase:  rf = 0 is at accelerating crest) SLAC linac tunnel research yard Linac-0 L =6 m Linac-1 L  9 m  rf   25° Linac-2 L  330 m  rf   41° Linac-3 L  550 m  rf   10° BC-1 L  6 m R 56   39 mm BC-2 L  22 m R 56   25 mm LTU L =275 m R 56  0 DL-1 L  12 m R 56  0 undulator L =130 m 6 MeV  z  0.83 mm    0.05 % 135 MeV  z  0.83 mm    0.10 % 250 MeV  z  0.19 mm    1.6 % 4.54 GeV  z  0.022 mm    0.71 % 14.1 GeV  z  0.022 mm    0.01 %...existing linac new rfgun 21-1b21-1d X Linac-X L =0.6 m  rf =  21-3b24-6d25-1a30-8c

3. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Complete & Detailed Design (cathode to dump) BC2LTU undulator L3 L2 cathode

4. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Machine Flexibility Operation at 0.2 to 1.0 nC and constant 87-m saturation length at 1.5 Å in/output beam linac setup jitter

5. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 RMS Bunch Length and Energy Spread sector-21sector-25sector-30FFTB++  zzzz

6. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 after BC1 after X-RF after L1 after DL1 after BC2 after L3 at und. after L2  z = 830  m  z = 190  m  z = 23  m  z = 190  m energy profile phase space time profile (2002 example)

7. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Location of Main Linac Diagnostics 5+ energy spread meas. stations (optimized with small  )...existing linac L0 rfgun L3L1 X L2  x,y EEEE EEEE EEEE EEEE 5+ emittance meas. stations designed into optics (  x,y ) slice measurements possible with transverse RF (L0 & L3) BPMs at or near most quadrupoles and in each bend syst. RF deflectors for slice  and  E measurements EEEE EEEE EEEE EEEE EEEE EEEE T-cav. T-cav.  x,y ?

8. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Linac ‘Commissioning’ (Physics) How to setup I pk = 3.4 kA,   1.2  m, etc. What to measure and what to adjust Simulations Longitudinal phase space Bunch Length Energy Spread (proj. & slice) Transverse phase space Projected Emittance Slice Emittance Will show a few examples, not full plan

9. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Setup of Linac-0 RF Approximate injector parameters needed prior to linac commissioning. RF-deflector at 1 MV Phasing L0-Linac RF-deflector  y  bunch length minimize energy spread with L0 RF phase

10. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Setup of Linac-1 RF Linac-1 RF phase scan (X-band off, BC1 bends at 295 MeV) Linac-X RF phase scan (BC1 bends at 250 MeV) set phase to  25˚  0.5˚ set phase to  160˚  0.5˚ 20-  m res. BC1 BPM L1 RF phase LX RF phase Turn on BC1 energy feedback Switch off BC2 chicane Use sec-25 RF-deflector to meas. bunch length (  z1 ) Adjust S-band RF phase (  0.5˚) to set  z1  195  10  m Linac-1 new rfgun 21-1b21-1d X

11. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Verify BC1 Setup with Wake-Loss Scan Scan Linac-1 S-band RF phase and use BC2 BPM to find maximum wake-induced energy loss across Linac-2 rfgun L1 X L2 (NO CSR) well tested at SPPS

12. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Setup of Linac-2 RF Linac-2 RF phase scan (BC2 bends at 5.9 GeV, or…) set phase to  41˚  0.5˚ 40-  m res. BC2 BPM L2 RF phase Turn on BC2 energy feedback Use sec-25 RF-deflector to measure length (  z2 ) Adjust L2 RF phase (  0.5˚) to set  z2  20  2  m Linac-3 phasing is trivial (  5˚) 5-  m res. LTU BPM L2 phase Scan Linac-2 phase & use LTU BPM to find max. wake-induced energy loss across Linac-3 (NO CSR) L2L3

13. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 RMS Transverse Beam Sizes: Cathode to Dump 100  m 10  m 1 mm undulator 4.0 mm (BC1) 2.6 mm (BC2)

14. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Emittance Meas. Simulation in LCLS OTR1,2,3WS11,12,13 BC1 Multiple OTR screens Multiple wire-scanners Quad-scans on single OTR Quad-scans on OTR with RF-deflector

15. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 135-MeV OTR x -profiles from tracking  x = 0.75 ± 0.04  m  x  118  m  x  49  m  x  120  m non-Gaussian

16. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Slice-Emittance Measurement Simulation RF-deflector at 1 MV slice OTR 10 times  y  bunch length quad scanned

17. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Slice-Emittance Measurement Simulation slice-5 Injector at 135 MeV with S-band RF-deflector at 1 MV = meas. sim. = calc. = y distribution = actual (same SLAC slice-  code used at BNL/SDL) (slice- y -emittance also simulated in BC1-center)

18. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Empirical BC1/BC2 Dispersion Correction Residual x -dispersion (and its angle) is precision minimized using ‘tweaker’ quads in the chicane actual data from SPPS chicane  x   /2 SPPS chicane with quads Correct  and (  ), orthogonally with 2 quads

19. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Moveable Chicanes BPM screen collimator quadrupole BPM critical for energy feedback (20  m resolution) offset: 0 to 32 cm (24 cm nominal) 3 cm contraction BPM screen collimator

20. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Field quality requirement too tight with fixed chicane... SPPS dipoles: |b 2 /b 0 | < 0.010% @ 2 cm (just barely met) |b 2 /b 0 | < 0.002% @ r = 2 cm  requires: |b 2 /b 0 | < 0.002% @ r = 2 cm (moveable chicane requires 0.070%) Also needed: BPM res. 20  mBPM res. 20  m BPM linearityBPM linearity profile monitorprofile monitor collimatorcollimator straight-through operationsstraight-through operations x 12 mm 45 mm 80 mm

21. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Linac-To-Undulator (LTU) 4  -wires, 6 collimators, 1 OTR energy centroid & spread meas. (OTR) (3  10  5 & 10  4 ) + collimation vertical bends  vertical bend 4.7 mr  horizontal jog 1.25 m  energy diagnostics  emit. diagnostics  bunch length diag.  collimators  CSR cancellation  branch points for future undulators  spontaneous undulator possible  vertical bend 4.7 mr  horizontal jog 1.25 m  energy diagnostics  emit. diagnostics  bunch length diag.  collimators  CSR cancellation  branch points for future undulators  spontaneous undulator possible

22. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Slice-Emittance Configuration for LTU slice-emit. meas. optics OTR33 nominal optics (proj. emit.) WS31-34 undulator… stopperinserted

23. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Slice-Emittance Measurements in LTU = meas. sim. = calc. = y distribution = actualx x z y LTU at 14 GeV with S-band RF-deflector at 24 MV

24. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Slice Energy Spread Measurements in LTU LTU at 14 GeV with S-band RF-deflector at 24 MV FEL goal  E /E  E /E  10  4  x  12  m

25. P. Emma, SLACLCLS FAC Meeting - April 29, 2004 Summary LCLS linac is operationally flexible Diagnostics have been incorporated into optical design and simulated (1 st pass) Two RF-deflectors allow time resolved measurements at low and high energy Tune-up algorithms have been considered, but more refinement is needed Feedback systems must maintain setup while tuning progresses