Mitigation of stimulated Raman scattering in the kinetic regime by external magnetic fields

B. J. Winjum, F. S. Tsung, and W. B. Mori
Phys. Rev. E 98, 043208 – Published 29 October 2018

Abstract

We show via particle-in-cell simulations that small normalized magnetic fields (ωc/ωp1) can significantly modify the evolution of backward stimulated Raman scattering (SRS) in the kinetic regime due to the enhanced dissipation of nonlinear electron plasma waves propagating perpendicular to magnetic fields. A magnetic field applied perpendicularly to the electron plasma wave (and driving light wave) increases the SRS threshold for kinetic inflation and decreases the amount of reflectivity when SRS is driven significantly above threshold. Analysis indicates that this arises because trapped electrons are accelerated as they surf across the wave, leading to the continual dissipation of the electron plasma waves over a wider range of wave amplitudes. The reduction in SRS reflectivity is most significant for a purely perpendicular field, although reduction also occurs for other angles; a parallel field can slightly increase single-speckle SRS but decreases multispeckle SRS. These simulations demonstrate the significance of magnetic-field contributions to nonlinear electron plasma wave damping with respect to nonlinear parametric decay instabilities; the simulation parameters are directly relevant for SRS in inertial confinement fusion devices and indicate that approximately 30 tesla magnetic fields might significantly reduce SRS backscatter.

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  • Received 17 February 2018
  • Revised 19 June 2018

DOI:https://doi.org/10.1103/PhysRevE.98.043208

©2018 American Physical Society

Physics Subject Headings (PhySH)

Plasma Physics

Authors & Affiliations

B. J. Winjum1,2, F. S. Tsung2,3, and W. B. Mori1,2,3,4

  • 1Institute for Digital Research and Education, University of California Los Angeles, Los Angeles, California 90095, USA
  • 2Particle-in-Cell and Kinetic Simulation Software Center, University of California Los Angeles, Los Angeles, California 90095, USA
  • 3Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
  • 4Department of Electrical Engineering, University of California Los Angeles, Los Angeles, California 90095, USA

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Issue

Vol. 98, Iss. 4 — October 2018

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