Studies of Asperity-Scale Plasma Discharge Phenomena

A combined experimental and computational simulation study of direct-current plasma discharge phenomena in small-length-scale geometries (<; 10 μm) is described. The primary goal is to study discharge breakdown characteristics in small-length-scale geometries as quantified by a modified Paschen breakdown curve and the quench characteristics in these discharges. A modified mesoscale friction tester apparatus is used for the experiments. A self-consistent nonequilibrium plasma model is used for the simulation studies. The model includes field-emission effects, which is a key process in determining small-length-scale breakdown behavior. The breakdown and quench curves obtained from the experiments and simulations showed the same general trends. Quantification of the heat fluxes from the simulations shows higher erosion at the cathode and a highly nonlinear heating behavior with applied overvoltages above the breakdown threshold.