Stochastic Processes in a Plasma

Abstract

Many processes in a plasma are stochastic rather than deterministic. Rather than considering an individual particle, a large number of particles is treated in terms of the velocity distribution function. In gas discharges, collisions of charged particles with neutral atoms lead to elastic scattering, excitation or ionization of the atom. Collisions also determine the transport processes, like mobility, conductivity and diffusion. Ambipolar diffusion is discussed at some length as the collective process that governs plasma losses towards the walls. Heating of plasmas is discussed for the electron gas in a gas discharge, and for achieving hot confined plasmas in magnetic or inertial fusion experiments.

“When I use a word”, Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.”

“The question is”, said Alice, “whether you can make words mean so many different things.”

Lewis Carroll, Through the Looking-Glass