Author: Muggli, P.
Paper Title Page
THPGW054 Generation and Delivery of an Ultraviolet Laser Beam for the RF-Photoinjector of the Awake Electron Beam 3709
 
  • V. Fedosseev, F. Batsch, C. Capelli, E. Chevallay, N. Chritin, S. Döbert, T. Feniet, F. Friebel, P. Gander, E. Granados, E. Gschwendtner, J. Hansen, C. Heßler, H. Panuganti, K.A. Szczurek
    CERN, Meyrin, Switzerland
  • M. Hüther, M. Martyanov, J.T. Moody, P. Muggli
    MPI-P, München, Germany
  
  In the AWAKE experiment, the electron beam is used to probe the proton-driven wakefield acceleration in a 10 m long rubidium vapor source. Electron bunches are produced using an RF-gun equipped with a Cs2Te photocathode illuminated by an ultraviolet (UV) laser pulse. To generate the UV laser beam a fraction of the infrared (IR) laser beam used for ionization of rubidium is extracted from the laser system, time-compressed to a picosecond scale and frequency tripled using nonlinear crystals. The transport line of the laser beam over the 20 m distance was built using rigid supports for mirrors and air-evacuated tube to prevent any possible beam pointing instabilities due to vibrations and air convection. Construction of the UV beam optical system enables appropriate beam shaping and control of its size and position on the cathode, as well as time delay with respect to the IR pulse, i.e. with respect to the plasma wakefield seeder. In this paper, we present the design of the UV beam line and results of its commissioning regarding IR/UV conversion, beam pointing stability, and means of beam control and monitoring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW054  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPGW072 Seeded Self-Modulation of Transversely Asymmetric Long Proton Beams in Plasma 3757
 
  • T.A. Perera, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • P. Muggli
    MPI-P, München, Germany
  • T.A. Perera, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Funding: This work is supported by Science and Technology Facilities Council grant ST/P006752/1.
The AWAKE experiment at CERN recently demonstrated the world’s first acceleration of electrons in a proton-driven plasma wakefield accelerator*. Such accelerators show great promise for a new generation of linear e-p colliders using ~1-10 GV/m accelerating fields. Effectively driving a wakefield requires 100-fold self-modulation of the 12 cm Super Proton Synchrotron (SPS) proton beam using a plasma-driven process which must be care-fully controlled to saturation. Previous works have modelled this process assuming azimuthal symmetry of the transverse spatial and momentum profiles **, ***. In this work, 3D particle-in-cell simulations are used to model the self-modulation of such non-round beams. Implications of such effects for efficiently sustaining resonant wakefields are examined.
* Adli, E., et. al. (2018). Nature, 561(7723), 363-367.
** Lotov, K. V. (2015). Physics of Plasmas, 22(10), 103110.
*** Schroeder, C. B., et. al. (2011). Phys. Rev. Lett., 107(14). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW072  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)