Study of the arc-anode interaction by a two-temperature model

A two-temperature multi-component model has been applied to study the anode region of a free-burning arc in the mixtures of argon and metal vapour. Description of the departure from the local thermodynamic equilibrium (LTE) follows by taking into account the different temperatures of the electrons and heavy particle component, diffusion of charge carriers, as well as evaporation and transport of the anode material (metal). The non-equilibrium mixture composition, corresponding transport coefficients and thermochemical data for the mixtures of gas and metal vapour are determined for the parameter range of interest. The energy balance of the anode has been derived by taking into account heat fluxes from the plasma, evaporation, as well as Ohmic heating of the anode. The properties of the non-equilibrium sheath near the anode are evaluated. Results for an argon arc in the presence of copper or iron vapour are presented and discussed.