Author: Bane, K.L.F.
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MOPOW044 Commissioning of the RadiaBeam / SLAC Dechirper 809
  • M.W. Guetg, K.L.F. Bane, A. Brachmann, A.S. Fisher, Z. Huang, R.H. Iverson, P. Krejcik, A.A. Lutman, T.J. Maxwell, A. Novokhatski, G. Stupakov, J. Zemella, Z. Zhang
    SLAC, Menlo Park, California, USA
  • M.A. Harrison, M. Ruelas
    RadiaBeam Systems, Santa Monica, California, USA
  • J. Zemella
    DESY, Hamburg, Germany
  • Z. Zhang
    TUB, Beijing, People's Republic of China
  We present results on the commissioning of the two-module RadiaBeam / SLAC dechirper system at LCLS. This is the first installation and measurement of a corrugated dechirper at high energy (4.4 - 13.3 GeV), short pulses (< 200 fs) and while observing its effect on an operational FEL. Both the transverse and longitudinal wakefields allow more flexible electron beam tailoring. We verify that, for a single module at a given gap, the strength of the longitudinal wake on axis and the dipole near the axis agree well with the theoretical values. Using direct longitudinal phase space mapping and X-ray FEL spectrum measurements we demonstrate the energy chirp control capabilities.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW044  
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TUPOW053 Measurement of Terahertz Generation in a Metallic, Corrugated Beam Pipe 1889
  • K.L.F. Bane
    SLAC, Menlo Park, California, USA
  • S.P. Antipov
    ANL, Argonne, Illinois, USA
  • M.G. Fedurin, K. Kusche, C. Swinson
    BNL, Upton, Long Island, New York, USA
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  Funding: Work supported by the Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-76SF00515
A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations*. We present results of a measurement of such an arrangement at BNL's Advanced Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 um. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam–-compared to the wavelength of the radiation–-to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. Our experimental set-up was simple and not optimized for the efficient collection of the radiation by e.g. the use of tapered horns. As such it can be considered a proof-of-principle experiment.
* K. Bane and G. Stupakov, NIM A677 (2012) 67-73.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW053  
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WEPOY019 Beam Optimization Study for an X-ray FEL Oscillator at the LCLS-II 3020
  • W. Qin, S. Huang, K.X. Liu
    PKU, Beijing, People's Republic of China
  • K.L.F. Bane, Y. Ding, Z. Huang, T.J. Maxwell
    SLAC, Menlo Park, California, USA
  • K.-J. Kim, R.R. Lindberg
    ANL, Argonne, Ilinois, USA
  The 4 GeV LCLS-II superconducting linac with high repetition beam rate enables the possibility to drive an X-Ray FEL oscillator at harmonic frequencies *. Compared to the regular LCLS-II machine setup, the oscillator mode requires a much longer bunch length with a relatively lower current. Also a flat longitudinal phase space distribution is critical to maintain the FEL gain since the X-ray cavity has extremely narrow bandwidth. In this paper, we study the longitudinal phase space optimization including shaping the initial beam from the injector and optimizing the bunch compressor and dechirper parameters. We obtain a bunch with a flat energy chirp over 400 fs in the core part with current above 100 A. The optimization was based on LiTrack and Elegant simulations using LCLS-II beam parameters.
* T. J. Maxwell et al., Feasibility study for an X-ray FEL oscillator at the LCLS-II, IPAC15, TUPMA028.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY019  
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