Particle motion near the resonant surface of a high-frequency wave in a magnetized plasma

Abstract

The motion of single charged particles in a magnetized plasma is studied using a Lagrangian formalism, applied to the average over a gyro-period, in the presence of an electromagnetic wave that is being resonantly absorbed by the medium. Near the resonance surface the wave amplitude has a gradient and the resulting particle drifts are shown to be consistent with the existence of a ponderomotive force, produced by the wave-field-gradient. The orbits are also obtained numerically to show how the drifting motion arises, and to study the case of high field-gradients, which is not described with the formal analysis.