PLASMA SHEATH EVOLUTION FROM PERTURBED ELECTRODES IN A NEGATIVE-ION PLASMA .2. EXPERIMENT AND PIC SIMULATION

The two-dimensional spatial and temporal evolution of a plasma surroun ding an electrode whose potential is suddenly decreased is experimenta lly investigated, The electrode contains a localized convex or a local ized concave perturbation. The quasineutral plasma consists of positiv e ions and various proportions of negative ions and electrons. The res ults are compared and contrasted with those that are obtained numerica lly using a particle-in-cell (PIG) simulation and those that had previ ously been obtained using a fluid-model code.