Nonlinear wave–particle scattering and absorption of electromagnetic and electrostatic waves in a magnetized plasma

Abstract

Nonlinear wave–particle scattering and absorption (nonlinear Landau and cyclotron damping) of electromagnetic and electrostatic waves by high energy or relativistic electrons in a homogeneous magnetized plasma are investigated theoretically by numerical analysis of general and simplified expressions of nonlinear wave–particle coupling coefficients. It is shown that strong nonlinear absorption of the extraordinary wave can occur by nonlinear scattering into the other extraordinary waves or Bernstein waves induced by high‐energy stationary or drifting electrons, and they can be accelerated. Nonlinear absorption by Bernstein wave or ordinary wave is weaker than that by extraordinary wave. These nonlinear absorption mechanisms can compete with linear absorption in a fusion plasma, and can exceed it for a sufficiently small k∥ρb. It is verified that nonlinear scattering of extraordinary waves can induce the effective acceleration of relativistic electrons in a fusion plasma.