Emittance preservation through density ramp matching sections in a plasma wakefield accelerator

ORAL

Abstract

In plasma wakefield acceleration, the witness beam's emittance needs to be preserved when it propagates through a plasma stage. The plasma includes density ramps at both the entrance and the exit. Using the Wentzel-Kramers-Brillouin (WKB) solution of a single particle's motion, analytical expressions for the evolution of the beam emittance and the Twiss parameters in an arbitrary adiabatic plasma profile are provided neglecting the acceleration of the beam inside the plasma. It is shown that the beam emittance can be preserved under the matching condition even when the beam has an initial energy spread. It is also shown that the emittance growth for an unmatched beam is minimized when it is focused to the same vacuum plane for a matched beam. The emittance evolution from 3D QuickPIC simulation results agree well with the theoretical results. The theoretical and simulation results are also used to analyze parameters for a proposed experiment on the FACET II facility.

* Work supported by DOE HEP DE-SC0010064, DOE SciDAC under a FNAL subcontract 644405, and by NSF 1806046.

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Authors

  • Yujian Zhao

    University of California, Los Angeles

  • Weiming An

    Beijing Normal University

  • Xinlu Xu

    SLAC National Accelerator Laboratory, UCLA

  • Fei Li

    University of California, Los Angeles, UCLA

  • Lance Hildebrand

    University of California, Los Angeles

  • Mark Hogna

    SLAC National Accelerator Laboratory, SLAC - Natl Accelerator Lab

  • Vitaly Yakimenko

    SLAC National Accelerator Laboratory, SLAC - Natl Accelerator Lab

  • Chan Joshi

    University of California, Los Angeles, University of California Los Angeles

  • Warren Mori

    University of California, Los Angeles, University of California Los Angeles, Departments of Physics and Astronomy & Electrical and Computer Engineering, University of California, Los Angeles, UCLA