Mechanisms of stimulated Raman scattering in direct-drive plasmas

ORAL

Abstract

Planar target experiments performed at the National Ignition Facility (NIF) suggest that stimulated Raman scattering (SRS) is dominant at the ignition scale [M.J. Rosenberg {\it et al}., PRL {\bf 120} 055001 (2018)], and that the subsequent preheat can be near levels which degrade the performance of directly driven implosions [A.A. Solodov {\it et al}., Phys. Plasmas {\bf 27} 052706 (2020)]. Definitive conclusions require a valid extrapolation of the observed scattered light and a detailed understanding of the contributions of several instability processes. To help resolve this, recent experiments on the OMEGA EP laser in which similar SRS signatures were observed at scale-lengths intermediate between NIF and OMEGA were analyzed using a new ray-tracing model. The model allows the various SRS contributions to the observed scattered light spectrum to be determined. The relevance to ignition-scale plasmas and implications for preheat will be presented.

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Authors

  • Jason Myatt

    University of Alberta, Univ of Alberta, Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada

  • Steven Hironaka

    Univ of Alberta

  • A.A. Solodov

    Laboratory for Laser Energetics, University of Rochester, NY, Laboratory for Laser Energetics, U. of Rochester, Laboratory for Laser Energetics, University of Rochester

  • M.J. Rosenberg

    Laboratory for Laser Energetics, University of Rochester, NY, LLE, University of Rochester, Laboratory for Laser Energetics, University of Rochester, LLE, Univ. of Rochester, Laboratory for Laser Energetics, University of Rochester

  • R. Follett

    University of Rochester, Laboratory for Laser Energetics, University of Rochester, NY, Univ. of Rochester

  • Wolf Seka

    Retired