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LCLS-II Design and FEL R&D

LCLS-II Design and FEL R&D. Tor O. Raubenheimer for the LCLS and LCLS-II teams. LCLS Concept: Fourth Generation Workshop 20 Years Ago. Herman Winick’s Study Group. Claudio Pellegrini. Herman Winick. Engaged Bjorn Wiik and Gerd Materlik during sabbaticals at SLAC.

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LCLS-II Design and FEL R&D

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  1. LCLS-II Design and FELR&D Tor O. Raubenheimer for the LCLS and LCLS-II teams

  2. LCLS Concept: Fourth Generation Workshop20 Years Ago Herman Winick’s Study Group Claudio Pellegrini Herman Winick Engaged Bjorn Wiik andGerdMaterlik duringsabbaticals at SLAC C. Pellegrini, A 4 to 0.1 nm FEL Based on the SLAC Linac, Workshop on Fourth Generation Light Sources, February, 1992 High Brightness Electron Beams Workshop, 2013

  3. 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) Far Experiment Hall High Brightness Electron Beams Workshop, 2013

  4. beam parked here Nov 2008… Commission Jan-Aug 2008 Commission Mar-Aug 2007 LCLS commissioning ended Oct. 2009 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 % 6 MeV z  0.83 mm   0.05 % 135 MeV z  0.83 mm   0.10 % Linac-X L =0.6 m rf= -160 Linac-0 L =6 m rf gun L0-a,b Linac-3 L 550 m rf  0° Linac-1 L 9 m rf  -25° Linac-2 L 330 m rf  -41° 25-1a 30-8c 21-3b 24-6d ...existing linac 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 SLAC linac tunnel research yard • Generation of lowemittance beam • Preservation of 6D brightness in accelerator and compressors • Undulators meeting tolerance and trajectory control High Brightness Electron Beams Workshop, 2013

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

  6. 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 <<10fs 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

  7. 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 1approved 2012: March- Critical Decision 3aapproved 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 New Underground Experiment Hall High Brightness Electron Beams Workshop, 2013

  8. 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

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

  10. 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: 4thundulator in existing tunnel, 2 more instruments High Brightness Electron Beams Workshop, 2013

  11. 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

  12. 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

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

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

  15. Hard X-Ray Self-SeedingNew Capability in LCLS Operation Nature Photonics (2012)

  16. 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

  17. iSASEexperiment • 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) iSASE SASE

  18. TW FEL: LCLS Strong Tapering Studies experiment simulation • 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 %) J. Wu, et al High Brightness Electron Beams Workshop, 2013

  19. TW FEL: LCLS Divergence StudiesSpecifying 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

  20. 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

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

  22. HXR Beam Splitting at LCLSIt works!! High Brightness Electron Beams Workshop, 2013

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

  24. DELTA Undulator for Polarization Control • 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

  25. 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

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

  27. 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

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