1. LCLS Status and Micro-Bunching Workshop at LBNL Torsten Limberg

2. Workshop Home Page

3. Workshop 0: ‘S2E & Instabilities’ in Zeuthen 2003

4. Zeuthen 2003

5. Laser ‘Heater’

6. Gain Calculations Zeuthen 2003

7. More Gain Calculations Zeuthen 2003

8. Back to LBNL Workshop: ‘Presentations’ Page

9. Talk Layout Tour Through the Workshop Program The LCLS COTR Problems and its Laser Heater LCLS Status

10. Program… Microbunching Workshop II – LBNL, 6-8 October, 2008 Semi-Final Program Schedule [last updated 2 October 2008] Monday, 6 October Introduction 9:00 – 9:20 9:00-9:05 Welcome, S. Gourlay, LBNL AFRD Head 9:05–9:20 Workshop Goals + Facilty Info. “Nuts & Bolts”, W. Fawley, LBNL Session I - Observations of Microbunching 9:20-12:30 Chairman: M. Cornacchia 9:20-9:50 Microbunching Observations at LCLS -- Z. Huang, SLAC 9:50-10:20 Microbunching Observations at FLASH -- B. Schmidt, DESY 10:20-10:50 Investigation of Microbunching Instability at the SCSS test accelerator -- K. Togawa, SPRING-8 10:50-11:40 Discussion & Coffee Service 11:40-12:10 Studies of fragmentation in electron beam energy spectra at SDL –- T. Shaftan, BNL Laser pulse shaping and beam structures at SDL -- S. Seletskiy, BNL 12:10-12:40 COTR and SASE from Compressed Beams -- A. Lumpkin, FNAL

11. Program… Session II - Theory and Simulation 14:00 - 18:00 Chairs: A. Zholents (pre-break) & G.Stupakov (post-break) 14:00-14:30 Overview and Recent Progress in uBI Theory and Simulation S. DiMitri, Trieste 14:30-15:45 Contributed talks on uBI Theory and Simulation: Modeling uBI Growth in the SPARX Configurations, C. Vaccarezza, INFN/Roma Nonlinear Correction to the Gain of the Microbunching Instability Seeded by Shot Noise, M. Venturini, LBNL Large-Scale Simulation of Microbunching Instability in the Berkeley FEL Linac Studies, J. Qiang, LBNL A Vlasov-Maxwell Solver to Study Microbunching Instability in the FERMI@ELETTRA First Bunch Compressor System, G. Bassi, Daresbury; J. Ellison, UNM; K. Heinemann 16:45-17:20 Contributed Talks on uBI Simulation + Modeling Existing Experiments: Wisconsin FEL Bunch Compressor Modeling, R. Bosch, U. Wis. Accelerator Design Concepts and Simulation Issues Relevant to the Microbunching Instability, Y. Kim, PSI Unrecognized Singularity in the Field of a 1-D Evolving Bunch, R. Warnock, SLAC LSC Microbunching from Shot Noise and Comparison with LCLS Results, D. Ratner

12. Program… Session III - Cathode, Laser, & Injector Physics Relevant to uBI Initialization & Growth 9:00 - 12:30 Chairperson T. Limberg 9:00-9:30 Cathode Emission Physics and Origins of Non-uniformity – K. Jensen, NRL 9:30-10:00 Laser Photocathode Physics & Observations Relevant to μBI -- D. Dowell, SLAC 10:00-10:30 Post-cathode Dynamical Evolution of E-beam Non-Uniformities -- P. Piot, NIU/Fermilab 11:15-12:30 Contributed talks on uBI Initialization & Growth in Cathode/Injector Regions: Possible Sources of Non-Uniform Emission,no, Velocity Bunching!, M. Ferrario, INFN/Frascati 3D Study of Effects from Inhomogeneities upon the Minimum Achievable Emittance, M. Quattromini, NEA/Frascati Microbunching Instability in Velocity Bunching, D. Xiang, SLAC Simulation of Propagation of Cathode Region Modulations in the FERMI Injector, G. Penco & P. Craievitch, Sincrotrone Trieste

13. Program… Session IV - Diagnostics & Control 13:30-17:45 Chairpersons, D. Dowell (pre-break) & M. Ferrario (post-break) 13:30-14:15 Current state-of-art in OTR physics & diag. setup – R. Fiorito, U Md., & A. Lumpkin, FNAL 14:15-14:40 LCLS OTR setup and COTR studies – H. Loos, SLAC 14:40-15:05 COTR observations at FLASH – B. Beutner, PSI LCLS Laser Heater plans – P. Emma, SLAC FERMI Laser Heater plans – S. Spampinati, Sincrotrone Trieste 16:00-17:15 Contributed talks on Diagnostics and Control: E-beam High-Frequency Content on the Bunch Length Measurement and Longitudinal Feedback, J. Wu, SLAC Two Stage, Single Shot IR CTR Spectrometer, S. Wesch, DESY Compressing Electron Bunches with Solenoids, A. Zholents, LBNL COTR Mitigation with a Tilted OTR Foil, G. Stupakov, SLAC 17:15-17:45 Discussion

14. Program… Near-Term Future Plans at Different Labs 9:00-10:20 Plans @ different labs including expt. verification/benchmarking of uBI theory & simulation, followed by open general discussion DESY FLASH & XFEL plans – T. Limberg FERMI Plans -- Injector microbunching characterization using a low energy deflecting cavity BNL plans – S. Seletskiy Frascati Plans - M. Ferrario ANL/FNAL Plans, A. Lumpkin Shanghai plans for uBI expt. studies– Z. Huang, SLAC, speaking for D. Wong, Shanghai Microbunching Experimental Plans at the Upcoming PSI 250 MeV injector – Y. Kim, PSI Daresbury Plans --- P. Williams

15. The LCLS COTR Problem No COTR Low gain COTR High gain COTR OTR Screens downstream of ‘dogleg’ not usable with design machine parameters

16. Scanning the Dogleg Quad

17. The LCLS Laser-Heater P. Emma, for The LCLS Commissioning Team LBNL µ -BI Meeting Oct. 7, 2008 LCLS Layout and Design Status of Installation Commissioning Issues Experiments?

18. OTR screens (7) YAG screens (7) Wire scanners (7) Dipole magnets (8) Beam stoppers (2) S-band RF acc. sections (5) RF Gun Solenoid GunSpectrometer RFDeflector X-band RF acc. section BC1 L1S L0a L0b 2-km point in 3-km SLAC linac LCLS Injector Layout 135-MeVSpectrometer EmittanceScreens/Wires EmittanceScreen/Wires 135 MeV 6 MeV 250 MeV TD11stopper Commissioned in ‘07 Laser-Heater

19. FEL limit LCLS Slice Energy Spread Tolerance Z. Huang et al., http://prst-ab.aps.org/abstract/PRSTAB/v7/i7/e074401 ~40 keV at 1 nC operating point

20. The LCLS Laser Heater (135 MeV) suggested by Saldin et al.

22. Laser Heater Simulations Z. Huang et al., FEL’04 Example of longitudinal phase space at 14 GeV with 8% initial modulation at 150- µ m modulation

23. Layout of the Laser Heater Optical System in the Laser Lab IR Laser System UV Conversion Unit Path Length Adjuster PH1 UV beam PC & polarizer Energy control Waveplate & polarizer PH2 Pulse Stretcher Shutter 3 lens Telescope To streak camera to vertical transport tube Adjustment of the telescope changes the beam size in the heater-undulator Sasha Gilevich

24. photo diode MH2 MH3 wave plate shutter OTRscreens powermeter Layout of the Laser Heater Optical System in the Injector Vault Sasha Gilevich MH4, MH3, MH2 - Motorized mirrors MH2 & MH3 are closed-loop control Waveplate and polarizer in front of both cameras vacuum transport to LH transport to the tunnel MH4 758 nm VHCcamera CH1 camera eeee

25. Injector Vault (Oct. ’07) transverse RF deflector RF gun (+ Dave) 6-135 MeV booster linac OTR screens & wire- scanners

26. Injector Vault (Oct. ’08)

27. IR & UV Laser Vertical Transport in Vault

28. Laser Table in the Injector Vault

29. Laser Heater Table in the Vault MH3 MH2 CH1 VHC on motorized XY stage To powermeter WP CH1 WP VHC

30. Laser Heater Table in the Vault Waveplate From MH2 50% beamsplitter To VHC MH1

31. IR Beam at Center of “Undulator” ~Sep. 30, 2008

32. Laser Heater Controls Panel Matt Boyes

33. Damping of COTR? (1 nC, 40 keV rms heating) BC1: COTR suppression for: 2  E /E 0 R 56 >> COTR suppression for: 2  E /E 0 R 56 >>  (40 keV)/(250 MeV)  (39 mm) = 39 µ m >> 1 µ m BC2: COTR suppression for: 2  E /E 0 C 1 R 56 >> COTR suppression for: 2  E /E 0 C 1 R 56 >>  (40 keV)/(4.3 GeV)  4.5(25 mm) = 7 µ m >> 1 µ m similar numbers at 250 pC with  E = 20 keV

34. RF Deflector (LOLA) + special lattice configuration in spectrometer allows fine measurement of time-sliced energy spread (to <6 keV)  E  6 keV rms (40  m) OTR screens (7) YAG screens (7) Wire scanners (7) Dipole magnets (8) Beam stoppers (2) S-band RF acc. sections (5) RF Gun Solenoid GunSpectrometer RFDeflector X-band RF acc. section BC1 L1S L0a L0b 2-km point in 3-km SLAC linac 135-MeVSpectrometer EmittanceScreens/Wires EmittanceScreen/Wires 135 MeV 250 MeV TD11stopperLaser-Heater

35. Laser Heater Commissioning Schedule laser heater commissioning All laser-heater systems will be ready by Nov. 3, 2008, except the LH- undulator (magnet vendor was late) LH-undulator will be installed in Dec. or Jan. FEL begins commissioning in March (must have LH ready) Ideas for reasonably well thought out experiments are welcome There is not limitless time available. Pressures to establish FEL arise quickly after March 15, 2009.

36. LCLS Commissioning Status P. Emma, for The LCLS Commissioning Team LCLS SAC Meeting October 20, 2008 LCLS Machine Performance Estimated FEL Power Present Stability Ultra-Short Pulse Possibilities

37. Linac Coherent Light Source at SLAC Injector (35º) at 2-km point Existing 1/3 Linac (1 km) (with modifications) Near Experiment Hall Far Experiment Hall Undulator (130 m) X-FEL based on last 1-km of existing linac New e  Transfer Line (340 m) 1.5-15 Å X-ray Transport Line (200 m)

38. LCLS Accelerator Layout 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  0° BC1 L  6 m R 56   39 mm BC2 L  22 m R 56   25 mm DL2 L =275 m R 56  0 DL1 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 % 4.30 GeV  z  0.022 mm    0.71 % 13.6 GeV  z  0.022 mm    0.01 % Linac-X L =0.6 m  rf =  21-1 b,c,d...existing linac L0-a,b rfgun 21-3b24-6d X 25-1a30-8c undulator Commission Mar-Aug 2007 Commission Jan-Aug 2008 Nov 2008… X-rays in spring 2009 beam parked here

39. Phase-II Commissioning Highlights (2008) Injector Commissioning: Apr-Aug, 2007 (DONE) Phase-II Commissioning: Dec-Aug, 2008 (DONE) Great drive-laser uptime (99%) and good performance Projected emittances 0.7-1.6  m at 0.25 nC, 10 GeV Routine 30-Hz e  to 14 GeV (~24/7 with ~90% up-time) Bunch compression fully demonstrated down to 1-2 µ m Many beam & RF feedback systems running well Electron bunch appears bright enough to drive 1.5-Å FEL 20-pC bunch with 0.14- µ m emittance (& ~10 fs length?)

40. Laser Spatial and Temporal Shaping in 2008 Temporal shape (6.6 ps FWHM) Spatial shape on cathode using iris S. Gilevich, G. Hays, P. Hering, A. Miahnahri, W. White 99% Drive Laser up time! 2R = 1.4 mm 2008 6.6 ps 2008

41. Design and Typical Measured Parameters (Aug. 2008) Parametersymboldesignmeasuredunit Final linac e  energy  mc 2 13.613.6MeV Bunch charge Q10.25nC Initial bunch length (rms)  z0 0.90.75mm Final bunch length (rms)  zf 208-10 mmmm Projected emittance (injector)  x,y 1.20.7-1.0 μmμmμmμm Slice emittance (injector)  s x,y 1.00.6 μmμmμmμm Projected emittance (linac end)  L x,y 1.50.7-1.6 μmμmμmμm Single bunch repetition rate f12030Hz RF gun field at cathode EgEgEgEg120115MV/m Laser energy on cathode ulululul25020-150 μJμJμJμJ Laser diameter on cathode 2R2R2R2R1.51.2mm Cathode quantum efficiency QE60.7-7 10  5

42. OTR screen 95% area cut Gaussian overlay not used Projected Emittance <1.2 μm at 1 nC (135 MeV)  x = 1.07 μm  y = 1.11 μm meetsinjectorgoals

43. Bunch Compression & CSR Measured after BC2 (0.25 nC)  z > 25  m BC2 (4.3 GeV) BSY (14 GeV) TCAV (5.0 GeV) 550 m  z < 5  m old screen used L2 4 wires  z  2  m nominal

44. L0 gun L3L2 X DL1BC1 DL2 L1 z1z1z1z1 1111 1111 V1V1V1V1 z2z2z2z2 2222 2222 V2V2V2V2 3333 V3V3V3V3 0000 V0V0V0V0 Laser & Electron-Based Feedback Systems D. Fairley, J. Wu BPMs CER detectors Longitudinal Loops Stabilize: DL1 energy BC1 energy BC1 bunch length BC2 energy BC2 bunch length Final energy BC2 Steering Loop Laser Transverse Loops Stabilize: Laser spot on cathode Gun launch angle Injector trajectory X-band cavity position Linac trajectory (2) Undulator traj. (future)

45. Bunch Length & Energy Feedback Systems Q = 0.25 nC  Q 2  1/2 /Q = 1.5% bunchcharge DL1 energy BC1 energy BC2 energy Final e  energy BC2 peak current BC1 peak current 216 ± 12 A 2170 ± 217 A 0.09% rms 0.03% rms 0.05% rms 0.03% rms Charge feedback: CSR-based bunch length monitor

46. Normalized phase space centroid jitter after BC1 (~4% of rms beam size) D. Ratner Stability is not so far from our goal (~10%) … near end of linac (10-15% of rms beam size) Thanks to Controls group for new BPM electronics! RMS A xN = 14% RMS A yN = 9%  E/E jitter  0.03%  Q/Q jitter  1.5% RMS A xN = 3.9% RMS A yN = 3.4% Q = 0.25 nC 1-  beam size

47. Now measure BPM jitter both with transverse RF OFF, and then ON (at constant phase)  t  ±0.6 ps slope =  2.34 mm/deg 9  m rms 110  m rms TCAV ON TCAV OFF BPM Y Position (mm) Measuring Bunch Arrival Time Jitter eeee V(t)V(t)V(t)V(t) S-band (2856 MHz) BPM Timing Jitter (w.r.t. RF) = (110  m)/(2.34 mm/deg) = 0.047 deg  46 fsec rms Q = 0.25 nC

48. long weekend run at 0.25 nC with no tuning Emittance Near End of Linac Over Long Weekend (3.3 days) May 24, 2008 00:01 to May 27 09:00  (  x  y ) 1/2 = 1.04  m

49. Beam Appears Bright Enough for FEL Saturation at 0.15 nm Calculation based on measured end-of-linac projected emittance values, measured peak current, and design undulator parameters (assuming undulator alignment and  0.01% rms slice energy spread – not yet measurable) M. Xie method, with wakes FEL Power 3D Gain Length FEL Power 3D Gain Length

50. Time-sliced x-Emittance at Very Low Charge 20 pC, 135 MeV, 0.6-mm spot diameter, 400 µm rms bunch length (5 A) TAIL (not same data) Also measured at 0.6 µm at 250 pC & 1.2-mm laser spot diameter (40 A) 0.14 µm

51.  z  1  m ? 8 kA? LiTrack (no CSR) Measurements and Simulations for 20-pC Bunch at 14 GeV Photo-diode signal on OTR screen after BC2 shows minimum compression at L2-linac phase of -34.5 deg. Horizontal projected emittance measured at 10 GeV, after BC2, using 4 wire-scanners. Y. Ding LCLS FEL simulation at 1.5 Å based on measured injector beam and Elegant tracking,with CSR, at 20 pC. LCLS FEL simulation at 1.5 Å based on measured injector beam and Elegant tracking, with CSR, at 20 pC. 1.5 Å, 3.6  10 11 photons I pk = 4.8 kA   0.4 µm SIMULATED FEL PULSE

52. Simulated 20-pC Bunch at 4.3 GeV: Approaching a Single Longitudinally Coherent Spike Y. Ding 15 Å 15 Å, z = 25 m, 2.4  10 11 photons, I pk = 2.6 kA,   0.4 µm (power profile at z = 25 m varies from shot to shot due to noisy startup) 1.2 fs z = 25 m LCLS FEL simulation at 15 Å based on measured injector beam and Elegant tracking,with CSR, at 20 pC. LCLS FEL simulation at 15 Å based on measured injector beam and Elegant tracking, with CSR, at 20 pC.

53. time (fs) Power (GW) 0105 LCLS BC2 bunch compressor chicane 0-150 fs 2 fs 2-Pulse Production with 2 slots 0-6 mm 0.25 mm pulses not coherent

54. LCLS Installation and Commissioning Time-Line LTU/Und/Dump Install Re-commission Inj/BC2 to SL2 LTU/UndComm. First Light in FEE PEP-II run ends FEE/NEH Install PPS Cert. LTU/Dump FEH Install CD-4 (7/31/2010) X-Rays in NEH First Light in FEH NEH Operations/ Commissioning JJFFMMAAMMJJJJAASSDDJJFFMMAAMMJJJJAASSOONNDDJJFFMMAAMMJJJJ ON A A 2008 2009 2010 2008 2009 2010 Down PPS A A M M now Linac/BC2 Commissioning FEEComm. May 2, 2008 FEH Hutch BO Und. Seg. Install