EVOLUTION OF CATHODIC MICROPROTRUSIONS IMMERSED IN DENSE-PLASMAS

A model has been developed to simulate the in interaction between dens e (order of n(e) = 10(16) cm(-3)) plasmas and the naturally occuring m icroprotrusions on cathode surfaces, Heating and cooling of an ellipso idal two-dimensional (2-D) model microprotrusion is simulated in order to achieve the time-dependent behavior in terms of electron emission and erosion of the microprotrusion, Thermo-field emission is taken int o account for the investigation of the electron emissivity of the tip, The 2-D model shows distinct differences to a one-dimensional (I-D) m odel in the scope of ''ignition'' of emissive and erosive behavior, In particular, it is found that due to ion heating, a 2-D protrusion can easily be ignited within ranges of plasma parameters and cathode volt age drop where 1-D models fail to explain the experimentally observed ignition of cathode spots on metal surfaces.