Thermoplastic deformation, erosion and emission processes in cathode spots of vacuum discharge

Both moving and stationary cathode spots are considered in whose elementary volumes the heat exchange is effected due to the spot motion, heat conductivity, evaporation front displacement, Joule heating, melting heat and thermoplastic deformation. The boundary conditions account for the surface heat source due to bombardment with charged particles with regard for Nottingham heat and emission cooling, heat removal as a result of evaporation and heat exchange due to the mutual irradiation of plasma and electrode. As a result of these calculations, the changes of temperatures, maximum rate of erosion, current density, erosion coefficient area of spots, current and charge in cathode spots in time were determined for a flat molybdenum cathode and cold cathode. The dynamics of the spot and cathode region parameters variation was studied using the technique. The current density was determined on the assumption of a thermo-autoelectronic mechanism taking into account the emission rate increase because of thermal stresses and explosive emission