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

TL;DR

This study demonstrates through simulations that small external magnetic fields can suppress stimulated Raman scattering in plasma, potentially improving inertial confinement fusion performance by reducing backscatter.

Contribution

It reveals how perpendicular magnetic fields modify SRS evolution in the kinetic regime, introducing a new method to control plasma instabilities.

Findings

Magnetic fields increase the SRS threshold.

Magnetic fields decrease SRS reflectivity.

Approximately 30 Tesla fields can significantly reduce backscatter.

Abstract

We show via particle-in-cell simulations that small normalized magnetic fields ($\omega_c/\omega_p \ll 1$) applied perpendicularly to a light wave can significantly modify the evolution of backward stimulated Raman scattering (SRS) in the kinetic regime. The presence of the magnetic field increases the threshold for kinetic inflation and decreases the amount of reflectivity when SRS is driven significantly above threshold. Analysis indicates 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 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.