Diamagnetic drift effects on ion Bernstein mode propagation in a plasma slab

Abstract

A one-dimensional infinite-order differential equation that describes the propagation of small amplitude electrostatic waves through a uniformly magnetized inhomogeneous plasma slab is derived. The spatially varying coefficients of the equation may be written in terms of an arbitrary density profile function provided that the velocity space distribution of the equilibrium is Maxwellian and the plasma is charge neutral. Ion Bernstein waves with frequencies between the first and second ion cyclotron harmonics and wavelengths along the density inhomogeneity larger than the ion Larmor radius are adequately modeled by truncating the differential equation at second order. Using a single mode electrostatic antenna to investigate the role of the diamagnetic drift on Bernstein wave propagation, a wavenumber dependence in the position of the low density cutoff for propagation is found, resulting in a preferential coupling of the antenna to waves with moderate kz∥ B propagating antiparallel to the ion diamagnetic drift. Moderate levels of Bernstein wave activity inside the plasma are demonstrated for an antenna located in the evanescent region.