Two-dimensional self-consistent modelling of the arc/cathode interaction

Abstract

A theory based on the literature works is developed to define a self-consistent model of the arc–cathode interaction in thermal plasma domain. The proposed model, applied in this paper in a two-dimensional coordinate system includes a physical description of the arc–cathode interaction, the cathode bulk, the sheath, the pre-sheath and the local thermodynamic equilibrium plasma column.This model allows assuming the electric current conservation through a two-temperature treatment of the sheath and pre-sheath regions. This model has been applied in a free burning arc configuration in an argon gas with a cylindrical tungsten cathode and current intensity equal to 200 A. The orders of magnitude of the current density and of the heat flux are, respectively, 106 A m−2 and 107 W m−2.Three parametric studies are performed: on the ionization layer length, on the value of the secondary emission coefficient and on the formulation of the electrical conductivity in the pre-sheath. The size of the ionization layer and the chosen value of the secondary emission coefficient have a significant influence on the properties of the discharge.