2-DIMENSIONAL SHEATH EVOLUTION IN A NEGATIVE-ION PLASMA

The spatial and temporal evolution of the components of a plasma surro unding a 90 degrees convex and a 90 degrees concave electrode whose po tential is suddenly decreased in a three-component plasma is numerical ly investigated. The quasineutral plasma consists of positive ions and various proportions of negative ions and electrons. The results are c ompared and contrasted with those that are obtained in a normal two-co mponent plasma. The transient or ion matrix sheath is identified and i ts subsequent evolution is investigated. Effects of perturbations in t he electrode are investigated. (C) 1996 American Institute of Physics.