Collisions and collisional transport—I. Particle collisions

Abstract

Abstract This chapter discusses the collisional scattering of particles, and some of the transport processes which they engender in plasmas. It pays attention to the basic descriptions and properties of binary collisions between charged particles, and between charged particles and neutrals (molecules). The kinetic theory of gases, in its simplest classical model, considers a gas as a dilute ensemble of small billiard balls. These molecules generally move in straight lines; however, when two of them encounter each other, there is a collision which produces an instantaneous deviation of their orbits. After the collision, the trajectories return to being quasi-linear. Considering the various particles that are encountered in a gas (atoms and molecules, some of which are possibly ionized), the chapter investigates the two types of collisions: elastic collision and inelastic collision.