The two-dimensional spatial and temporal evolution of the components o
f a plasma surrounding an electrode whose potential is suddenly decrea
sed is investigated numerically. The electrode contains a localized co
nvex or a localized concave volt age perturbation. The quasineutral pl
asma consists of positive ions and various proportions of negative ion
s and electrons. The results are compared and contrasted with those ob
tained with a uniform electrode under identical plasma conditions.