Simulation of diffuse and spot modes of current transfer to thermionic cathodes

Summary form only given, as follows. The present contribution represents a second part of a work concerned with a detailed study of various aspects of the interaction of a high-pressure plasma with refractory cathodes. In the first part (M S Benilov and M D. Cunha, Heating of refractory cathodes by high-pressure arc plasmas I, J Phys D Appl Phys, vol 25, No 14, pp 1736-1750, 2002), a solution on the plasma side was considered, results of numerical modelling of the diffuse mode of current transfer under conditions of a low-current arc were given and a good agreement with the experimental data was shown. The aim of the present contribution is to report on results of numerical modelling of diffuse and axially symmetric spot modes in a wide current range and to analyze, on the basis of numerical results and analytical treatment, general features of interaction of a high-pressure plasma with refractory cathodes in a wide current range.