USE OF THE FOKKER-PLANCK EQUATION IN HIGH-FIELD TRANSPORT PROBLEMS

The Fokker-Planck drift-diffusion equation is often used to describe B rownian motion of a particle in thermal equilibrium with the surroundi ng medium. The present paper shows that the equation has the ability t o describe charged particle transport far from equilibrium such as occ urs in the presence of a high electric field in a neutral gas or a sem iconducting solid. These transport problems are usually tackled by mea ns of the Boltzmann transport equation, but the Fokker-Planck approach is mathematically simpler, and gives insight into the statistics of e nergy-exchange processes and their thermalization capacity. (C) 1998 A merican Association of Physics Teachers.