Collisions and Basic Plasma Physics

Abstract

Key parameters of a plasma are discussed, including plasma oscillations and Debye length. The Coulomb cross section is introduced, and the importance of screening is discussed. The Coulomb logarithm is discussed from the perspective of defining the collective nature of plasma. The rates of momentum and energy exchange are found through the basic collision rates. The application of the slowing-down equation to the problem of runaway electrons is described. The Fokker-Planck equation is shown, with the collision operator obtained from the Rosenbluth potentials. The particle drift due to crossed electric and magnetic fields is derived. The magnetic moment is defined, and drifts induced by the gradients and curvature of a magnetic field are given, along with the polarization drift for a changing electric field. The magnetization current is found, and the overall diamagnetic current in a magnetized plasma is given by combining the drift and magnetization terms, showing that the particle effects lead to the basic pressure balance derived from fluid theory.