LCLS-II Design and FEL R&D Summary of project scope key milestones funding profile commissioning by LCLS operations path to CD-2 priority of longer tunnel urgency of getting CF bids mention FAC Tor O. Raubenheimer for the LCLS and LCLS-II teams

LCLS Concept: Fourth Generation Workshop 20 Years Ago C. Pellegrini, A 4 to 0.1 nm FEL Based on the SLAC Linac, Workshop on Fourth Generation Light Sources, February, 1992 Herman Winick’s Study Group Claudio Pellegrini Herman Winick Engaged Bjorn Wiik and Gerd Materlik during sabbaticals at SLAC High Brightness Electron Beams Workshop, 2013

Linac Coherent Light Source Facility First Light April 2009, CD-4 June 2010 Injector at 2-km point Existing Linac (1 km) (with modifications) UCLA New e- Transfer Line (340 m) Undulator (130 m) Near Experiment Hall X-ray Transport Line (200 m) High Brightness Electron Beams Workshop, 2013 Far Experiment Hall

LCLS commissioning ended Oct. 2009 6 MeV z  0.83 mm   0.05 % 135 MeV z  0.83 mm   0.10 % 250 MeV z  0.19 mm   1.6 % 4.50 GeV z  0.022 mm   0.71 % 13.6 GeV z  0.022 mm   0.01 % beam parked here Linac-X L =0.6 m rf= -160 Linac-0 L =6 m rf gun L0-a,b Linac-1 L 9 m rf  -25° Linac-2 L 330 m rf  -41° Linac-3 L 550 m rf  0° 25-1a 30-8c ...existing linac 21-3b 24-6d 21-1 b,c,d undulator L =130 m X BC1 L 6 m R56 -39 mm BC2 L 22 m R56 -25 mm undulator DL1 L 12 m R56 0 DL2 L =275 m Commission Mar-Aug 2007 Commission Jan-Aug 2008 Nov 2008… SLAC linac tunnel research yard Generation of low emittance beam Preservation of 6D brightness in accelerator and compressors Undulators meeting tolerance and trajectory control High Brightness Electron Beams Workshop, 2013

LCLS Operational Performance (480 eV – 10 keV)  (280 eV – 10 keV) High Brightness Electron Beams Workshop, 2013

LCLS Achievements Exceptional e- beam quality from RF gun (gex,y  0.4 mm) Pulse length easily adjustable for users (60 - 500 fs FWHM) with <<10 fs pulses at low charge (20 pC) Wider photon energy range: 280 - 10000 eV (design was: 830 - 8300 eV) Peak FEL power >70 GW (10 GW in CDR) Pulse energy up to 6 mJ (2 mJ in CDR) 96.7% accelerator availability, 94.8% photon availability Total of 133 publications, 35 in high impact journals High Brightness Electron Beams Workshop, 2013

Linac Coherent Light Source II Injector @ 1-km point Sectors 10-20 of Linac (1 km) (with modifications) 2010: April- Critical Decision 0 approved 2011: October- Critical Decision 1 approved 2012: March- Critical Decision 3a approved 2012: August- Critical Decision 2 2013: June- Critical Decision 3b ?? 2018: Sept. First FEL Light 2019: Sept. Critical Decision 4 Bypass LCLS Linac In PEP Line (extended) New Beam Transport Hall SXR, HXR Undulators X-ray Transport Optics/Diagnostics High Brightness Electron Beams Workshop, 2013 New Underground Experiment Hall

LCLS-II Accelerator for 250 pC, 120 Hz Injector, linac, and compression parameters are all very similar to LCLS-I, but not exact High Brightness Electron Beams Workshop, 2013

LCLC-II Parameter Space Photon Energy vs Beam Energy Calculation by H-D Nuhn High Brightness Electron Beams Workshop, 2013

LCLS-II Greater Capacity Dedicated new injector at Sector 10 Two new SASE undulator x-ray sources, both variable gap High Field Physics Soft X-Ray Experiment Station Immediately: 4X increase in operations hours for soft x-rays Generally, soft x-ray experiments run one-at-a-time Immediate 20% increase in operations hours for hard x-rays Since hard x-ray instruments will someday run simultaneously, perhaps 2 or even 3 at a time, this can mean nearly 20% more time per station Future: Room in new experiment hall for at least 3 more new instruments with new scientific capabilities Future: 4th undulator in existing tunnel, 2 more instruments High Brightness Electron Beams Workshop, 2013

LCLS-II Enhanced Capability LCLS-II will provide expanded spectral range using two beamlines and variable gap undulators Up to 13 keV (above Selenium K-edge) @ 10.5-13.5 GeV Down to 250 eV (Carbon K-edge) @ 7-10 GeV 300 meter undulator tunnel Adequate space to accommodate future enhancements: Options for BW control: SS, iSASE, pSASE, … Two-color generation Polarization control TW peak power Details will be determined by ongoing LCLS R&D program High Brightness Electron Beams Workshop, 2013

LCLS-I R&D Studies Improving LCLS-II Design Many beam physics studies on LCLS and NLCTA that are helping clarify LCLS-II design Injector studies to optimize and verify performance: rf gun, laser heater, BC1, and BC2 CSR and bunch shaping studies for longitudinal phase space Jitter studies to understand performance limits Component studies – LCLS-II designs are similar in many cases Gain length, angular divergence, operational stability measurements to help specify x-ray characteristics Other R&D studies enhancing the LCLS-II design Polarization control, self-seeding, & improved diagnostics Improved-SASE (iSASE) and Purified SASE (pSASE) Two-color generation, … High Brightness Electron Beams Workshop, 2013

LCLS-I FEL R&D Projects LCLS-I R&D will clarify LCLS-II upgrades TW CTF (Cathode Test Facility) High Brightness Electron Beams Workshop, 2013

Hard X-ray Self-Seeding High Brightness Electron Beams Workshop, 2013

Hard X-Ray Self-Seeding New Capability in LCLS Operation Nature Photonics (2012)

Improved SASE (iSASE) Improve longitudinal coherence by increasing the longitudinal slippage Narrow SASE bandwidth without fixing the central photon energy. Pulse Intensity is less sensitive to energy jitters LCLS proof-of-principle experiment: Use detuned undulator as phase shifts Detune every other undulator after U5 J. Wu, A. Marinelli, Pellegrini, FEL2012

SASE: (red) 1.21 mJ; average spectrum (FWHM 17 eV) iSASE experiment SASE: (red) 1.21 mJ; average spectrum (FWHM 17 eV) iSASE: (blue) 0.21 mJ; average spectrum (FWHM 5 eV) Single shot spectrum (13.8 GeV,150 pC) SASE iSASE

TW FEL: LCLS Strong Tapering Studies Envelope of measured power similar to on-energy simulations Large sensitivity to energy jitter as previously observed 1% taper demonstrated blue (on-energy), black (+0.1 %), red ( -0.1 % ), magenta (-0.2 %) experiment simulation J. Wu, et al High Brightness Electron Beams Workshop, 2013

TW FEL: LCLS Divergence Studies Specifying LCLS-II Apertures X-ray stay clear (mirrors, diagnostics, energy attenuator) all depend on x-ray beam sizes Measurements of LCLS Angular Divergence Y. Feng, J. Krzywinski, J. Turner, J. Welch High Brightness Electron Beams Workshop, 2013

XTCAV: LCLS X-Band Transverse Cavity A deflecting cavity has been installed after the undulator to measure the longitudinal phase space (t, DE/E) of the e- and g beams P. Krejcik Y. Ding Commissioning to start soon! High Brightness Electron Beams Workshop, 2013

XTCAV: e- and g Longitudinal Phase Space FEL off FEL on Reconstructed e- profile Reconstructed g profile Soft X-Rays Hard X-Rays Y. Ding High Brightness Electron Beams Workshop, 2013

HXR Beam Splitting at LCLS It works!! High Brightness Electron Beams Workshop, 2013

Two-color FEL Single slotted foil to control pulse duration Chicane to control delay A. Lutman, R. Coffee, Y. Ding, et al. Magnetic Chicane 1st undulator section K1 e- x-ray 1st Color 2nd undulator section 2nd Color Controlled Delay K2 Color separation 19 eV Eb = 5800 MeV and Eg = 1.5 keV

DELTA Undulator for Polarization Control Flexible post-saturation taper Second-harmonic afterburner Simple upgrade to LCLS undulator Cornell 0.3-m Delta undulator (A. Temnykh) LCLS 1-m prototype H.-D. Nuhn, E. Kraft High Brightness Electron Beams Workshop, 2013

Soft X-Ray Self Seeding Photon energy 500-1000 eV (expandable to 300-1200 eV) Resolving power ~ 5000 Fit in one undulator section (U9), < 4m in length SLAC, LBNL, PSI collaboration High Brightness Electron Beams Workshop, 2013

SLAC X-ray FEL R&D roadmap LCLS-II injector LCLS-II completion 2011-12 2013-14 2015-16 2017-18 2019-20 X-ray seeding & brightness HXRSS iSASE TWFEL Soft X-Ray Self-Seeding ECHO-7 ECHO-75, laser phase error error Zhirong Huang HHG efficiency and control E-beam brightness & manipulation ASTA (Cathode R&D) Injector R&D ITF-FACET2: advanced beam generation, high-energy compression and seeding Ultrafast techniques Temporal diagnostics & timing Attosecond & mode-locking x-rays THz & Polarization THz THz Facility Options Polarization control Technology development X-ray spectrometer, beam sharing Multi bunches, detectors, novel undulators, high-rep. rate Completed Ongoing Under development

Summary LCLS has been a great success Very flexible beam operations allows for wide range of photon science studies R&D program is defining new capability Short fs-scale bunches Wide photon energy range; photon beam splitting Self-seeding with >0.01% BW; iSASE Two color operation Polarized x-rays Strongly tapered operation LCLS-II will be the next addition to the SLAC photon science portfolio  expands LCLS capability and capacity greatly High Brightness Electron Beams Workshop, 2013