Theory of a Weakly Turbulent Plasma

Abstract

A characteristic feature of a plasma is the existence of a spectrum of collective oscillations or plasma waves (plasmons). The frequency and velocity of propagation of these waves are determined by the wave vector and by the gross parameters of the plasma such as the density, the mean velocity spread, the magnetic field, etc., and this situation is a reflection of the fact that all of the particles in the plasma are involved in the plasma oscillations. The situation is different, however, when one examines the damping (or growth) of the oscillations. Damping (growth) is determined by the “fine details” of the particle distribution in phase space, for example, by the derivative of the velocity distribution function; this situation reflects the specific role played by resonance particles (i.e., particles for which the following condition is satisfied: ω _k — kv = nωn; n = 0, 1, 2, …; here, ω _k and k are the frequency and wave vector that characterize the wave, v is the particle velocity, and ω_H = eH/mc). These particles are capable of exchanging energy with the waves and can thus amplify or damp it.