P. Emma, et al. LCLS Operations Lectures

Transcription

1 P. Emma, et al. LCLS Operations Lectures LCLS 1

2 LCLS Accelerator Schematic 6 MeV 135 MeV 250 MeV σ z 0.83 mm σ z 0.83 mm σ z 0.19 mm σ δ 0.05 % σ δ 0.10 % σ δ 1.6 % Linac-0 L =6 m rf gun L0-a,b Linac-1 L 9 9 m rf 25 ϕ rf Linac-X L =0.6 m rf = 160 ϕ rf Linac-2 L 330 m rf 41 ϕ rf 4.30 GeV σ z mm σ δ 0.71 % Linac-3 L 550 m rf 0 ϕ rf 13.6 GeV σ z mm σ δ 0.01 %...existing linac DL1 L 12 m R b,c,d X BC1 L 6 6 m mm R b 24-6d SLAC linac tunnel BC2 L 22 m mm R a 30-8c Commission in Jan Commission in Jan DL2 L =275 m 56 0 R 56 undulator L =130 m research yard 2

3 Complete & Detailed Optics (cathode to dump) dump cathode L2 BC2 L3 sec-21 sec-30 LTU undulator muon plug wall Full MAD files at: ssrl.slac.stanford.edu/lcls/linac/optics/ 3

4 LCLS Installation and Commissioning Time-Line Drive-Laser Commissioning Drive-Laser Install undulator LTU/und. First FEL hall ready Install Light linac/bc2 Install First Spont. Light MM J J A S O N D J F M A M J J A S O N D J F M A M J J June 2006 Gun/Inj./BC1 Install (8/21 1/5) Gun/Inj./BC1 Commissioning linac/bc2 Commissioning FEL Comm. LTU/undulator Commissioning 4

5 LONG BELLOWS ASSEMBLY SPOOLS FROMVALVE SEAL UHV ALL METAL GATE VALVES RF Gun TREATMENT CHAMBER PORCUPINE CATHODE HOLDER VACUUM PUMPS 6 MeV L0a RF section Injector Layout 62 MeV L0b RF section gun spectrometer 135 MeV Transverse RF deflector L1 RF section (21-1b) 1b) main SLAC Linac injector spectrometer sector 20 sector 21 5

6 LCLS Injector Commissioning Dates ( 06( - 07) July 24: Aug. 29: Dec. 18: Dec. 19: Dec. 20-Jan. 1: Jan. 2: Jan. 12: Jan. 12-Feb. 4: Sector-20 ready for laser installation Laser installation complete Virtual cathode fully characterized (ready to install gun) RF gun installation starts (10 days) + pre-beam checkout Holidays VVS s switched on (RF power available) First laser UV-light on cathode! Electrons in GTL and gun-spect spect.. (RF processing L0a,b, L1, LX) Feb. 5: Beam into L0a, L0b and down to 135-MeV spect. Feb. 20: ~June: Beam into main linac (to TD11 dump) Take beam down full linac (to BSY SL2 stopper) 6

7 OUT OF DATE Microsoft Project Commissioning Schedule DOWN 2007 DOWN

8 pass-1 OUT OF DATE pass-2 pass DOWN pass-1 pass DOWN 8

9 pass-1 pass DOWN OUT OF DATE pass DOWN 9

10 Commissioning Definition and Strategy All components have been installed, aligned, connected, and initially verified by the system engineer, then commissioning starts. Commissioning Sequence (1-4)( 1. Pre-Beam Checkout (tunnel and MCC) Controls/software testing, check cameras, snail hunt, etc Magnet polarities, cable connections, verify motion-control, etc 2. Beam-based Hardware and Software Checkout Establish beam transport, RF setup, MPS/BCS tests, etc Checkout of all wires, screens, BPMs, toroids, magnets, etc 3. First-Order Optics: Measurement and Correction Steering, transmission, oscillation data, feedback setup, etc Beta and dispersion matching, beam-base base align key quads, etc 4. Full Beam Characterization: Measurement and Correction Measure emittance, energy spread, distributions - correct Measure beam sensitivities, optimize tuning, beam experiments No (serious) emittance measurements until all hardware/software checked out! 10

11 Electron Commissioning Organization Project Director J. Galayda Commissioning Don P. Emma Alternating Weekly Run Coordinator One Lead Physicist per shift Shift Physicists Controls & System Engineers MCC & Laser Operators 11

12 LCLS Injector Commissioning Day 24-Hour Cycle (7 days/week, 1/2/07 to 9/1/07,, 32 total weeks) DAY DAY SHIFT SHIFT (8:00-16:00) 1 lead lead physicist, 1 physicist, 1 controls eng., eng., 1 sys. sys. engineer, 1 LCLS LCLS operator, 1 laser laser operator SWING SHIFT SHIFT (16:00-24:00) 1 lead lead physicist, 1 physicist, 1 LCLS LCLS operator, 1 laser laser operator OWL OWL SHIFT SHIFT (0:00-8:00) 1 LCLS LCLS operator, 1 laser laser operator? 12

13 Parameters Parameter RF rate Beam rate Drive-laser rate Bunch charge Drive-laser pulse length Gun gradient Value 30 Hz 30 Hz 120 Hz pc 10 ps fwhm 120 MV/m Comments 30 Hz in linac (possible short-term term 120-Hz rate in L0- BC1 for feedback tests, etc) Hz in gun for short time to verify full rate 30 Hz e beam as baseline possible short term 120- Hz tests in L0-BC1 for feedback tests, etc 120-Hz at all times shutters provide e rate as required above depends on QE and diagnostics some short spans at 10 pc later in 07 we explore 1-nC1 10-ps fwhm startup with possibility of 6-ps 6 at 0.2 nc later early laser tests may provide path to more convenient pulse-length length changes Set as goal, although 110 MV/m is adequate in 07 13

14 Issues Controls will be mixed (SLC & epics) and capabilities may be limited initially Most High-Level Applications (emittance, bunch length, feedback) must done through MATLAB as a temporary solution Most LCLS physicists not yet experienced in SLAC control room with SLC controls Help from operations group will be needed LCLS Lecture Series + Workshop in Oct.? 14

15 Q = 1 nc f = 120 Hz G = 120 MV/m γε x,y = 1 µm τ = 10 ps I = 100 A E = 6 MeV solenoid RF gun cathode RF Photo-Cathode Gun spec. dipole UV laser YAG screens e e 15

16 LONG BELLOWS ASSEMBLY SPOOLS FROMVALVE SEAL UHV ALL METAL GATE VALVES RF Gun YAG screen TREATMENT CHAMBER PORCUPINE CATHODE HOLDER VACUUM PUMPS YAG screen YAG screen YAG screen trajectory (BPMs) emittance (+ (+ slice) energy spread (+ (+ slice) bunch length (+ (+ dist.) charge (+ (+ dark dark current) gun spectrometer Injector Diagnostics YAG screen Transverse RF deflector OTR & wire OTR & wire OTR & wire main SLAC Linac injector spectrometer 16 YAG OTR & wire YAG & OTR

17 Injector Through BC1 Commissioning no laser-heater until 08 RF deflector γε x,y γε and slice σ E E 17

18 Injector Through BC1 Commissioning (2) BC1 relative bunch length monitors X-band RF σ E E slice γε y γε x,y stopper 18

19 Setup of Linac-1, X-band X RF Phases 20-µm m res. BC1 BPM 20-µm m res. BC1 BPM LX RF phase L1 RF phase Linac-1 1 RF phase scan (X-band off, BC1 bends at 295 MeV) Linac-X X RF phase scan (BC1 bends at 250 MeV) rf gun new new set phase to 25 ±0.5 set phase to 160 ±0.5 Linac b 1b 21-1d 1d X Turn on BC1 energy feedback Switch off BC2 chicane Use sec-25 RF-deflector to meas. bunch length ( (σ z1 ) Adjust S-band S RF phase (±0.5( 0.5 ) ) to set σ z1 195 ±10 µm 19

20 40-µm m res. BC2 BPM Setup of Linac-2 2 RF 5-µm m res. LTU BPM wake-loss scan L2 RF phase Linac-2 2 RF phase scan (BC2 bends at 5.9 GeV, or ) L2 phase Scan Linac-2 2 phase & use LTU BPM to find max. wake-induced energy loss across Linac-3 set phase to 41 ±0.5 L2 L3 Turn on BC2 energy feedback Use sec-25 RF-deflector to measure length ( (σ z2 ) Adjust L2 RF phase (±0.5( 0.5 ) ) to set σ z2 20 ± 2 µm Linac-3 3 phasing is trivial (±5 )( 20

21 Longitudinal Beam-Based Based Feedback gun V 0 δ 0 σ z1 σ z2 L0 L0 δ 1 δ 2 δ 3 ϕ 1 V 1 ϕ 2 V 2 V 3 L1 X L2 L3 DL1 BC1 BC2 DL2 21

22 Location of Main Linac Diagnostics 5+ energy spread meas. stations (optimized with small β) 5+ emittance meas. stations designed into optics ( ( ψ x,y ) BPMs at or near most quadrupoles and in each bend syst. RF deflectors for slice ε and σ E measurements (L0 & L3) rf gun L0 L0 T-cav. γε x,y γε x,y γε x,y T-cav. γε x,y...existing linac L1 X L2 L3 γε x,y σ E σ E σ E E E E σ E E σ E E 22

23 Slice-Emittance Measurement Simulation slice OTR 10 times RF-deflector at 1 MV σ y bunch length 135 MeV quad scanned 23

24 Slice-Emittance Measurement Simulation Injector (135 MeV) with S-band RF-deflector at 1 MV (same SLAC slice-ε code used at BNL/SDL) (slice-y-emittance emittance also simulated in BC1-center) = meas. sim. = calc. = y distribution = actual DL1 slice-emit emit on WS02 slice-5 24

25 y-slice-emittance Measurement in BC1 Q21201 scanned ±20% 3.9 mm 0.1 mm 25

26 weak quad setting Slice ε y Measurements at BNL undulators linac (off) linac dump dump 75 MeV 75 MeV 5 MeV medium quad setting strong quad setting 200 pc, 100 A, 75 MeV Data from DUVFEL at BNL: : W. Graves, et al. 26

27 vertical bends Linac-To To-Undulator (LTU) energy centroid & spread meas. (OTR) ( & 10 4 ) + collimation 4 ε-wires, wires, 6 collimators, 1 OTR vertical vertical bends bends horiz. horiz.. jog jog m energy energy diagnostics diagnostics emit. emit. diagnostics diagnostics collimators collimators branch branch points points for for future future undulators undulators 27

28 Slice Energy Spread Measurements in LTU σ E /E 10 4 LTU at 14 GeV with S-band S RF-deflector at 24 MV σ x 12 µm FEL goal 28

29 Summary Injector commissioning starts very soon (Laser:: Aug. 06, Electrons: : Jan. 07) Phase-II of commissioning comes in Jan. 08 LCLS group will need continual help from operations group LCLS is a 30-year machine this is just the start 29