Kinetic Modeling of Initiation of Explosion Center on Cathode Under Dense Plasma

A kinetic 1-D spherically symmetric model of heating of microprotrusion (with a curvature radius of 1 $\mu\hbox {m}$ ) on the cathode under dense plasma is developed. The kinetic model is a model of 1D3V PIC/DSMC type. The model takes into account the main types of elastic and inelastic collisions of particles in the plasma as well as evaporation and thermofield electron emission from the cathode. The surrounding plasma parameters in the model are fixed on the boundary placed at a certain distance from the microprotrusion. The applied voltage drop is also fixed on the same boundary. The further evolutions of the plasma, current, and cathode temperature are calculated self-consistently taking into account the influence of the plasma generated during the process. The calculations have shown that, under the certain condition, thermal runaway is developed and the cathode surface temperature reaches the critical one. However, this instability is not caused by microprotrusion Joule heating because the current density is comparatively small $(< 10^{8} \hbox {A}/\hbox {cm}^{2})$ at that moment.