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.