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

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

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 Smaller emittance, 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

FEL R&D Page 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 5 Charge from Norbert and Jo 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. To Jerry Hastings, Zhirong Huang (Jan. 21, 2011)

Overall program FEL R&D Page 6 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 A class of experiments that would benefit not only SLAC but the larger FEL community.

ParameterNowFuture Photon energy, keV Up to 10 Up to 100 Pulse repetition rate, Hz ≤ Pulse duration, fs ~2-300 < Coherence, transverse diffraction limited Coherence, longitudinal not transform limited transform limited Coherent photons/pulse2x x Peak brightness, ph/s mm 2 mrad 2 0.1% bandwidth Average Brightness, ph/s mm 2 mrad 2 0.1% bandwidth 4x Polarization linear variable, linear to circular X-ray FEL 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!

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

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

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

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

Schedule and costs Concept and Design4 months Construction and Installation5 months Commissioning6 shifts (8 hrs/shift)* * plus 2 weeks pre-beam checkout Concept and Design4 months Construction and Installation5 months Commissioning6 shifts (8 hrs/shift)* * plus 2 weeks pre-beam checkout Stages of Project Development: Cost Estimate0.94 M$ Add 30% Contingency1.22 M$ Cost Estimate0.94 M$ Add 30% Contingency1.22 M$ Project Costs: Est. Commissioning DateDec FEL R&D Page 12

FEL ON FEL OFF 13 time eeee zzzz 2×1 m dddd ssss   90° V(t)V(t)V(t)V(t) RF‘streak’ Dipole X-band TCAV energy DyDy 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 X-band Transverse Cavity (XTCAV) Y. Ding X-band rf freq = 11.4 GHz resolution fs-resolution electron and x-ray temporal diagnostics

 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 Hard X-Ray Single-Shot Spectrometer (HRSSS) FEL R&D Page 14 M. Yabashi, J. Hastings et. al. PRL 97, (2006) Glassy- carbon 1/  T 1/  c SASE spectral spikes (Optional) Designed operating range keV 10 keV Si Y. Feng

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

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 Multi-Bunch X-Ray Production (MBXRP) 8.4 ns FEL  Higher hit rate of virus in jet 1  m/10ns Sample source 2-Bunch lasing demonstrated F.-J. Decker Develop electron and photon multi-bunch diagnostics for reliable operation FEL R&D Page 16

Soft X-ray Polarization Control (SXRPC) linear vertical 500 eV … 500 eV– … 2. Circular Polarizer (Fundamental) Phase Shifter linear horizontal circular Lowest Cost; Reduced degree of polarization Degree of polarization fluctuates 1.Crossed Polarizer (Fundamental)– Fast Switching High degree of polarization; High intensity; Degree of polarization stable – Slow Switching Afterburner linear horizontal Existing LCLS undulatorAfterburner Exiting LCLS undulator Adding APPLE undulators to LCLS for polarization control Polarization Control Photon Range: 500 eV – 2000 eV Additional tapered undulator for HXRSS APPLE gap changes to Second Harmonic Afterburner H.-D. Nuhn (Advanced Planar Polarized Light Emitted)

THz/X-ray Pump Probe (THXXP) 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 A. Fisher FEL R&D Page 18

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) FEL R&D Page 19 Near Experimental Hall AMOSXRXPP Pulse pick-up location S. Moeller

FEL R&D Page 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 beamline R&D

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

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

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

FEL R&D Page 24 ITF for high-energy seeding/compression  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 J. Frisch

Seeding laser system Transform Limited Pulse “Chirped” Pulse Oscillator Amplifier Harmonics 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) A. Fry Seed Laser Phase Error Control Seeded spectra FEL R&D Page 25

SAC Meeting April 18-19, 2011 Charge: Evaluate the presented LCLS R&D projects: 1.Are the proposed R&D projects important from a science/LCLS user point of view? 2.Which do you consider the most important ? 3.Should other R&D projects be added at this time ? FEL R&D program presented to LCLS SAC FEL R&D Page 26

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

FEL R&D Page 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.