VELOCITY AUTOCORRELATIONS OF CHARGED PARTICLES IN A MAGNETOIONIC MEDIUM WITH APPLICATIONS TO TURBULENT DIFFUSION

Abstract

A system of charged particles in a slightly ionized medium is considered subject to (1) collisions with members of the neutral species, (2) a constant external magnetic field, and (3) a fluctuating force field, either external or representing the collision forces. On the assumption that their motions are satisfactorily described by the Langevin equation, the cross-correlation functions in time between velocity components of these charged particles are calculated. These functions may be used, as described elsewhere by the author, to describe the self-diffusion of the charged particles. The cases treated are: purely random external forcing, forcing by exponentially correlated (Markovian) forces, and forcing by a random series of pulses corresponding to collision forces.