Streaming Instabilities in Satellite Plasma Sheaths

The electrical equilibrium of a satellite at high altitudes, representing the balance between emission and accretion of charge at the satellite surface, requires for its existence the stability of the potential and charge distributions throughout the space surrounding the satellite. In the following, we consider the stability of equilibrium states of geometrically simple satellites illuminated by solar radiation and exposed to the charging environment of the rarefied plasmas at plasmaspheric and magnetospheric altitudes. Sufficient conditions for stability are established on strictly analytical grounds and, in the case of satellites large compared to the Debye length, ¿D, sufficient conditions for equilibria to be unstable are given. The stability of various equilibria are investigated numerically by means of a one-dimensional particle simulation of a collisionless plasma.