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

Abstract

Here, we show via particle-in-cell simulations that small normalized magnetic fields (ω_c/ω_p << 1) 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.

Authors:

Winjum, B. J. ^[1]; Tsung, F. S. ^[1]; Mori, W. B. ^[1]

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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States)

Publication Date:

Mon Oct 29 00:00:00 EDT 2018

Research Org.:

Univ. of California, Los Angeles, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1614554

Alternate Identifier(s):

OSTI ID: 1479615

Grant/Contract Number:  

SC0019010; NA0002953

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review E

Additional Journal Information:

Journal Volume: 98; Journal Issue: 4; Journal ID: ISSN 2470-0045

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Physics; Electrostatic waves & oscillations; Inertial confinement fusion; Laser-plasma interactions; Stimulated Brillouin & Raman scattering in plasmas; Wave-wave, wave-particle interactions