Group Velocity Measurements in Laser-Heated Capillary Discharge Waveguides for Laser-Plasma Accelerators

ORAL

Abstract

To date, the most energetic electron beams from laser-plasma accelerators have been produced using gas-filled capillary discharge waveguides, which increase the acceleration length by mitigating diffraction of the driving laser pulse. [1] To reach higher electron beam energies, lower plasma density is required to reduce bunch dephasing. However, confinement of the driver is reduced for lower plasma density, reducing the acceleration length. A laser-heated capillary discharge waveguide, where the discharge is heated by a coaxial laser pulse, was proposed to create a steeper density gradient at lower density. [2] Here, spectral-interferometric group velocity measurements in laser-heated capillary discharges are presented. Modification of plasma density and matched spot-size by laser-heating is demonstrated. Trends in on-axis plasma density and matched spot-size with discharge and laser parameters are characterized. [1] W.P. Leemans, et al, Physical Review Letters 113, 245002 (2014). [2] N.A. Bobrova, et al., Physics of Plasmas 20, 020703 (2013).

*Work supported by the U.S. Dept. of Energy, Office of Science, Office of High Energy Physics, under Contract No. DE-AC02-05CH11231. Additional support by the National Science Foundation under grant PHY-1415596.

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Presenters

  • Christopher V Pieronek

    • Lawrence Berkeley National Laboratory, USA, University of California-Berkeley, USA
    • Univ of California - Berkeley

Authors

  • Christopher V Pieronek

    • Lawrence Berkeley National Laboratory, USA, University of California-Berkeley, USA
    • Univ of California - Berkeley

  • Anthony J Gonsalves

    • Lawrence Berkeley Natl Lab
    • Lawrence Berkeley National Laboratory, USA
    • LBNL

  • Joost Daniels

    • Lawrence Berkeley National Laboratory, USA, Eindhoven University of Technology, The Netherlands
    • Lawrence Berkeley Natl Lab

  • Carlo Benedetti

    • Lawrence Berkeley Natl Lab
    • Lawrence Berkeley National Laboratory, USA

  • Jeroen van Tilborg

    • Lawrence Berkeley National Laboratory, USA
    • Lawrence Berkeley Natl Lab
    • LBNL

  • Jianhui Bin

    • Lawrence Berkeley National Laboratory, USA
    • Lawrence Berkeley Natl Lab

  • Wim Pieter Leemans

    • Lawrence Berkeley Natl Lab
    • Lawrence Berkeley National Laboratory, USA
    • Lawrence Berkeley Natl Lab, U.C. Berkeley
    • Lawrence Berkeley Natl Lab, Univ of California - Berkeley
    • LBNL, UC Berkeley