PLASMA SHEATH EVOLUTION FROM PERTURBED ELECTRODES IN A NEGATIVE-ION PLASMA

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.