Quasi-linear theory of a plasma

Abstract

In this work we present the fundamental ideas of a quasi-linear theory for a weakly turbulent plasma. We consider a number of plasma processes characterized by the excitation of collective degrees of reedom: the dynamics of the growth of noise in an unstable plasma, the interaction of a beam of charged particles with a plasma, and the damping of plasma waves. We discuss the properties of the stationary, weakly turbulent state that arises when a current flows through a plasma; the problem of anomalous plasma diffusion across a magnetic field is considered. We also investigate “threshold absorption” of high-amplitude waves, which is a mechanism for collisionless heating.