KINETIC SIMULATION OF A TIME-DEPENDENT 2-DIMENSIONAL PLASMA

The distribution function of ions is calculated in a two-dimensional p lasma with a rapidly expanding sheath, self-consistently with the elec trostatic potential, phi. The numerical procedure consists of a direct solution of an integral form of the kinetic equation. This solution r elies on the use of a simple form for the Green's function which descr ibes the time-evolution of the distribution, which has previously been used in one spatial dimension and is here extended to two dimensions. The electron density n(e) is assumed to be described by the Boltzmann relation, n(e) = n0 exp(ephi/kT(e)), allowing Poisson's equation to b e solved for phi self-consistently with the ion density. This procedur e is applied to describe the plasma surrounding a ''target'' to which is rapidly applied a large negative potential, as occurs in plasma sou rce ion implantation (PSII). The ion distribution striking the target is calculated to allow determination of the dose and depth profile. (C ) 1994 Academic Press, Inc