FEL R&D

1. FEL R&D Zhirong Huang May4, 2011 Pre-SPC Meeting for Accelerator R&D

2. 1010 LCLS LCLS-II Light Sources at ~1 Å Peak Brightness (photons/s/mm2/mrad2/0.1%-BW) storage rings H.-D. Nuhn, H. Winnick FWHM X-Ray Pulse Duration (ps)

3. Why FEL R&D? • Seeded FELs with Full Coherence are the next Frontier • Narrower bandwidth, stable pulse form • FEL efficiency is greatly enhanced with a tapered undulator • Smalleremittance, higher peak current • Advanced cathodes and guns • Bunch compression, mitigation of collective effects • Emittance exchange/conditioning • Ultrafast techniques and instrumentations to fully utilize XFELs • Average brightness enhancement • Special source and polarization are highly designable FEL R&D Page 3

4. National and International context • LCLS is the first and only hard x-ray FEL. • LCLS-II will be built in the next six years. • Next Generation Light Source (LBL) closes in on CD-0, needs extensive R&D on seeding etc. • Many XFEL projects on the international stage: SPring8 (Japan), FERMI (Italy), PSI (Switzerland), FLASH and FLASH-II (Germany), European XFEL, Pohang (Korea), Shanghai (China)… FEL R&D Page 4

5. Charge from Norbert and Jo To Jerry Hastings, Zhirong Huang (Jan. 21, 2011) • Identify and prioritize the experiments that should be executed at the LCLS, and if required at other SLAC accelerator test facilities. • Involve the FEL community in the design, preparation, execution, exploitation and potentially even the funding of these experiments. • Develop an integrated program that has near-term, mid-term and long-term goals and that spans the breadth of accelerator and x-ray based science and technology from basic physics to FEL science and into ultra short beam diagnostics. FEL R&D Page 5

6. Overall program • Two equally important categories • A class of experiments necessary to improve LCLS operation as well as those that will be instrumental in deciding what the detailed configuration of LCLS II • Aclass of experiments that would benefit not only SLAC but the larger FEL community. FEL R&D Page 6

7. X-rayFEL Parameters – Now and Future (C. Pellegrini et al., summary of FEL workshops.) red: parameter space to be developed • SLAC wants to be a big part of this future!

8. FEL R&D planning process Standing meeting to discuss FEL R&D plans. Identify projects, lead physicists and engineers. A concurrent task force led by Bob Hettel looks into test facilities for many R&D areas. Seek a variety of funding streams: AIP, MIE, BES, HEP R&D planning is ongoing, new ideas and projects will be addressed as they arise. Look for collaborations (national and international) and suggestions FEL R&D Page 8

9. FEL R&D Program with essential components • for LCLS II, NGLS and other FELs LCLS-II injector LCLS-II completion 2019-20 2011-12 2013-14 2015-16 2017-18 FEL Seeding schemes HXRSS SXRSS demo ECHO-7+ Laser & phase error control Beam brightness & manipulation CTF/GTF (Cathode, Gun) Injector studies (LCLS-II injector) ITF (Sector 0-9) to enable advanced beam generation, manipulation, compression and seeding at high energy Ultrafast techniques Temporal diagnostics & timing Attosecond x-ray generation THz & Polarization THz generation Polarization ctrl. Technology development Multi bunches, detectors, short-period undulators, high-rep. rate X-ray Beamline R&D

10. LCLS R&D Projects EXRLT (experimental x-ray to laser timing) XRSSS (X-ray single-shot spectrometer) HXRSS (hard x-ray self seeding) XTCAV (X-band trans. cavity) LCLS undulator SXRPC (Soft x-ray polarization control) XRDBL (X-ray R&D Beamline) MBXRP (Multi-bunch x-ray production) THXPP (THz/x-ray pump/probe) FEL R&D Page 10

11. Hard X-ray Self-Seeding (HXRSS) Self-seeding of 1-mm e- pulse at 1.5 Å yields 10-4 BWwith 20-pC mode. Undulatortaper provides 30brightness & 25 GW. P. Emma (SLAC), A. Zholents (ANL) FEL spectrum after the diamond crystal 1 GW ~25 GW Geloni, Kocharyan, Saldin (DESY) 3.2 m wall side

12. Schedule and costs Stages of Project Development: • Concept and Design4 months • Construction and Installation 5 months • Commissioning 6 shifts (8 hrs/shift)* • *plus 2 weeks pre-beam checkout • Est. Commissioning Date Dec. 2011 Project Costs: • Cost Estimate 0.94 M$ • Add 30% Contingency 1.22 M$ FEL R&D Page 12

13. V(t) X-band Transverse Cavity (XTCAV) fs-resolution electron and x-ray temporal diagnostics 2×1 m RF ‘streak’ Dipole e- Dy sz X-band rf freq = 11.4 GHz X-band TCAV energy time D 90° FEL OFF FEL ON resolution bs bd • High resolution, ~ few fs; • Applicable in all FEL wavelength; • Beam profiles, single shot; • No interruption with operation; • Both e-beam and x-ray profiles. e-beam x-ray Y. Ding

14. Hard X-Ray Single-Shot Spectrometer (HRSSS) • Provide missing LCLS capability for tuning SASE process • Measure pulse length similar to soft X-ray statistical method • Serve as prototype for LCLS-II XTOD spectrometer • Provide diagnostic for hard X-ray self-seeding M. Yabashi, J. Hastings et. al. PRL 97, 084802 (2006) Designed operating range 4 -13 keV (Optional) SASE spectral spikes 1/DT Glassy- carbon 1/tc 10 keV Y. Feng Si <555> FEL R&D Page 14

15. Exp. X-ray to Laser Timing (EXRLT) Measure x-ray to laser timing to <10fs (rms) • Hard x-rays: RF cavity timing • Soft x-rays: chirped continuumtechnique • Chirped continuum uses x-rays to induce a change in refractive index SiN Soft x-rays Ti:Sapph laser Spectrometer stacked spectra R. Coffee wavelength

16. Multi-Bunch X-Ray Production (MBXRP) Two bunches to serve SXR/HXR in LCLS-2 Two bunches for THz/X-ray Multiple bunches (separated by ~10s ns) to increase hit rate on samples 2-Bunch lasing demonstrated F.-J. Decker 8.4 ns Sample source Higher hit rate of virus in jet FEL  1m/10ns Develop electron and photon multi-bunch diagnostics for reliable operation FEL R&D Page 16

17. Soft X-ray Polarization Control (SXRPC) Adding APPLE undulators to LCLS for polarization control (Advanced Planar Polarized Light Emitted) • Crossed Polarizer (Fundamental) – Fast Switching Lowest Cost;Reduced degree of polarization Degree of polarization fluctuates Phase Shifter linear vertical 500 eV … linear horizontal Existing LCLS undulator Afterburner 2. Circular Polarizer (Fundamental) – Slow Switching High degree of polarization;High intensity; Degree of polarization stable linear horizontal circular 500 eV– … Exiting LCLS undulator Afterburner H.-D. Nuhn • Polarization Control Photon Range: 500 eV – 2000 eV • Additional tapered undulator for HXRSS • APPLE gap changes to Second Harmonic Afterburner

18. THz/X-ray Pump Probe (THXXP) A. Fisher • Laser-based THz sources are insufficient for pump-probe • LCLS can create a quasi-unipolar pulse with >1 GV/m and >100 µJ that is synchronized with x-rays FEL R&D Page 18

19. X-ray R&D Beamline (XRDBL) • Pulse stealing at 1 Hz (out of 120 Hz), available in parallel with normal LCLS operation • Provide a development and test area for hard x-ray • methods and instrumentation (for example: detectors) Pulse pick-up location Near Experimental Hall AMO SXR XPP S. Moeller FEL R&D Page 19

20. LCLS R&D Summary • Hard X-ray Self-Seeding:seeded FEL at hard x-ray regime • Single-shot diagnostics: temporal (X-band TCAV), spectral (hard x-ray spectrometer), timing (exp. x-ray laser timing) • Multi-bunch X-ray Production to increase rate, brightness • Synchronized pump/probe sources (THz/X-rays) • Control of radiation properties (polarization control) • X-ray beamlineR&D FEL R&D Page 20

21. Program Execution Plan • LCLS R&D projects will be managed uniformly • Each project has lead physicist(s), engineer(s) • Project scope, schedule, cost must be clearly defined • For example

22. Other R&D areas Echo-7 ITF for laser seeding at high energy Laser Detector … FEL R&D Page 22

23. ECHO-7 at NLCTA D. Xiang First ECHO signal 1590 nm laser on 795 nm laser on • ECHO is a novel harmonic generation technique from laser-beam interaction (seeding options for NGLS and LCLS-II SXR) Both lasers on ECHO 600 350 400 450 500 550 Radiation wavelength (nm) • 5th harmonic generated with ECHO technique • The facility is under upgrade for benchmark of ECHO theory at higher harmonic number (>=7) FEL R&D Page 23

24. ITF for high-energy seeding/compression J. Frisch • Collaborating with LBNL to develop a high-energy test facility (S0 ITF) to perform critical R&D (Echo-100, HHG seeding) for NGLS and other FELs • Based on the first 1 km of the SLAC linac, use an LCLS-like injector • Serve as a testbed for advanced beam generation, compression FEL R&D Page 24

25. Seed Laser Phase Error Control • Laser phase error is amplified by harmonic number N in harmonic generation FELs • Need to measure and control laser spectral phase to better than ~1/N ~ 10 mrad (for N ~ 100) Seeding laser system Transform Limited Pulse Oscillator Seeded spectra Amplifier “Chirped” Pulse Harmonics A. Fry FEL R&D Page 25

26. FEL R&D program presented to LCLS SAC • SAC Meeting April 18-19, 2011 • Charge: Evaluate the presented LCLS R&D projects: • Are the proposed R&D projects important • from a science/LCLS user point of view? • Which do you consider the most important ? • Should other R&D projects be added at this time ? FEL R&D Page 26

27. SAC defined categories Must do (self-seeding, single-shot diagnostics, Detector) General Benefit (multi-bunch, X-ray beamline) Smaller subset of users (THz, polarization) LCLS-II and wider community (Echo-7+, laser phase error) SAC comments that ‘real time’ data analysis/on-line data reduction are crucial for the users FEL R&D Page 27

28. Conclusions • LCLS, LCLS-II create excitement in FEL and x-ray sciences. • A vibrant FEL R&D program is an essential element of the SLAC future. • R&D projects are being pursued not only for LCLS, but also for the larger FEL community. • The program benefits from strong national and international collaborations. FEL R&D Page 28