Unified Non-equilibrium Modelling of Tungsten-Inert Gas Microarcs in Atmospheric Pressure Argon

Abstract

Analysis of the plasma parameters of a tungsten-inert gas microarc with a length of 0.4 mm is carried out by means of a unified one-dimensional model. The model solves the fluid equations for the particle and energy conservation of the electrons and the heavy species in the plasma, and the heat conduction in the thermionic cathode. The particle transport of the electrons and the ions is coupled with the Poison’s equation. The spatial distributions of the densities of the charged particles, the electric potential and field, the components of the electric current density, the heating mechanisms and the resulting temperatures of the electrons and heavy particles are discussed in detail for an electric current density of 106 A/m2. The discharge voltage, estimates of the Debye length, the near-electrode voltage drop, and the thickness of the regions of space charge adjacent to the electrodes are obtained for current densities in the range from 5.3 × 103 up to 2.3 × 106 A/m2.