Author: Loos, H.
Paper Title Page
TUOANO03
 Bunch Profile Measurement of the LCLS Electron Beam via Mid-IR Spectroscopy  
 
  • T.J. Maxwell, Y. Ding, A.S. Fisher, J.C. Frisch, H. Loos
    SLAC, Menlo Park, California, USA
  • C. Behrens
    DESY, Hamburg, Germany
  
  Funding: Work supported by US Department of Energy contract number DE-AC02-76SF00515.
For the generation of ultrashort x-ray FEL pulses, a similarly short, high-brightness electron beam is needed with compression tuned to the extent that a narrow energy spread can still be preserved. Further reduction of the nominal LCLS bunch length by lowering the bunch charge or employing an upstream, emittance-spoiling foil promises to reduce the pulse duration to the level of only a few femtoseconds, presenting a challenge to the temporal resolution of existing longitudinal diagnostics. In answer to this, we have recently commissioned a single-shot, middle-infrared spectrometer for the LCLS. Developed as a robust and cost-effective alternative to other femtosecond-scale beam diagnostics, coherent mid-IR beam radiation measurements and analysis are then employed to probe the LCLS beam just prior to the undulator. Results resolving beam structure to the few-fs level for 20 - 150 pC beams will be presented. Practical design challenges and diagnostic limitations will also be discussed. 		 
slides icon Slides TUOANO03 [2.337 MB]  
 
TUOBNO04
 Femtosecond Electron and X-ray Beam Temporal Diagnostics Using an X-band Transverse Deflector at LCLS  
 
  • Y. Ding, C. Behrens, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, T.J. Maxwell, J.W. Wang, M.-H. Wang, J.J. Welch
    SLAC, Menlo Park, California, USA
  • C. Behrens
    DESY, Hamburg, Germany
  
  X-ray free-electron lasers provide ultrashort x-ray pulses for multidisciplinary users. Temporal characterization of these ultrashort pulses with a femtosecond precision remains a challenging topic. At the Linac Coherent Light Source (LCLS), an X-band radio-frequency transverse deflector proposed in 2011 [*] has just been installed and commissioning of the RF system has started. By measuring the electron beam longitudinal phase space between lasing and non-lasing conditions, both the e-beam and x-ray temporal profiles can be reconstructed. We report the latest progress of the commissioning of the deflector and the measurements on the e-beam and x-ray pulse length with this deflector at LCLS. The resolution, stability and operational performance will also be discussed.
[*] Y. Ding et al., Phys. Rev. ST Accel. Beams 14, 120701 (2011) 		 
slides icon Slides TUOBNO04 [4.086 MB]  
 
TUPSO84 SLAC RF Gun Photocathode Test Facility 427
 
  • T. Vecchione, A. Brachmann, W.J. Corbett, M.J. Ferreira, S. Gilevich, E.N. Jongewaard, H. Loos, J. Sheppard, S.P. Weathersby, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.
A RF gun photocathode test facility has been commissioned at SLAC. The facility consists of a S-band gun, high power RF, a UV drive laser and beam diagnostics. Here we report on the capabilities of the facility demonstrated during commissioning. Currently the facility is being used to study in-situ laser processing of copper photocathodes. In the future the facility will be used to study fundamental gun and photocathode performance limitations and enhancement strategies. Eventually it is envisioned to integrate a load lock and plug into the gun enabling the evaluation of high performance surface sensitive semiconductor photocathodes and the incorporation of ex-situ surface science analytical techniques. 		 
 
WEPSO27 Recent LCLS Performance From 250 to 500 eV 554
 
  • R.H. Iverson, J. Arthur, U. Bergmann, C. Bostedt, J.D. Bozek, A. Brachmann, W.S. Colocho, F.-J. Decker, Y. Ding, Y. Feng, J.C. Frisch, J.N. Galayda, T. Galetto, Z. Huang, E.M. Kraft, J. Krzywinski, J.C. Liu, H. Loos, X.S. Mao, S.P. Moeller, H.-D. Nuhn, A.A. Prinz, D.F. Ratner, T.O. Raubenheimer, S.H. Rokni, W.F. Schlotter, P.M. Schuh, T.J. Smith, M. Stanek, P. Stefan, M.K. Sullivan, J.L. Turner, J.J. Turner, J.J. Welch, J. Wu, F. Zhou
    SLAC, Menlo Park, California, USA
  • P. Emma
    LBNL, Berkeley, California, USA
  • R. Soufli
    LLNL, Livermore, California, USA
  
  Funding: Work supported by US Department of Energy contract DE-AC02-76SF00515 and BES.
The Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs. The facility has been operating at X-ray energy from 500 to 10,000eV. Users have expressed great interest in doing experiments with X-Rays near the carbon absorption edge at 284eV. We describe the operation and performance of the LCLS in the newly established regime between 250 and 500eV.
[1] Emma, P. et al., “First lasing and operation of an ˚angstrom-wavelength free-electron laser,” Nature Pho-
ton. 4(9), 641–647 (2010).
 		 
 
WEPSO62 The IR and THz Free Electron Laser at the Fritz-Haber-Institut 657
 
  • W. Schöllkopf, W. Erlebach, S. Gewinner, G. Heyne, H. Junkes, A. Liedke, G. Meijer, V. Platschkowski, G. von Helden
    FHI, Berlin, Germany
  • H. Bluem, D. Dowell, K. Jordan, R. Lange, J. Rathke, A.M.M. Todd, L.M. Young
    AES, Medford, NY, USA
  • M.A. Davidsaver
    BNL, Upton, New York, USA
  • S.C. Gottschalk
    STI, Washington, USA
  • U. Lehnert, P. Michel, W. Seidel, R. Wünsch
    HZDR, Dresden, Germany
  • H. Loos
    SLAC, Menlo Park, California, USA
  
  A mid-infrared oscillator FEL with a design wavelength range from 4 to 50 μm has been commissioned at the Fritz-Haber-Institut in Berlin, Germany, for applications in molecular and cluster spectroscopy as well as surface science. The accelerator consists of a thermionic gridded electron gun, a subharmonic buncher and two S-band standing-wave copper structures. The device was designed to meet challenging specifications, including a final energy adjustable in the range of 15 to 50 MeV, low longitudinal emittance (< 50 keV-psec) and transverse emittance (< 20 π mm-mrad), at more than 200 pC bunch charge with aμpulse repetition rate of 1 GHz and a macro pulse length of up to 15 μs. Two isochronous achromatic 180 degree bends deliver the beam to the undulators, only one of which is presently installed, and to the beam dumps. Calculations of the FEL gain and IR-cavity losses predict that lasing will be possible in the wavelength range from less than 4 to more than 50 μm. First lasing was achieved at a wavelength of 16 μm in 2012*. We will describe the FEL system design and performance, provide examples of lasing, and touch on the first anticipated user experiments.
* W. Schöllkopf et al., MOOB01, Proc. FEL 2012.