Gas dynamics and electromagnetic processes in high-current arc plasmas. Part I. Model formulation and steady-state solutions

A three-dimensional computational model has been developed to study the effects of self-induced and external magnetic fields, as well as gassing effects, on arcs involved in switching devices. A commercial computational fluid dynamics code has been adapted and modified to model the fully coupled plasma flow, heat transfer, and electromagnetic field. In this paper, a model is developed to analyze a steady-state, two-dimensional axisymmetric air arc column at low current levels under conditions in which the effects of the self-induced magnetic field are negligible. The model is then extended to analyze a three-dimensional arc column at high current levels with the inclusion of self-induced magnetic effects. The effects of cathode size, distance from the electrode, current level, self-induced magnetic field, and natural convection on the arc plasma are investigated. Predictions from these models compare favorably with published analytical and experimental results. The influence of external transverse magnetic fields, as well as the presence of gassing materials, on a three-dimensional arc column in both steady-state and transient situations will be discussed in L. Z. Schlitz et al. [J. Appl. Phys. 85, 2547 (1999)]. (C) 1999 American Institute of Physics. [S0021-8979(99)01805-8].