Evaporation Dominated High Current Arcs in Narrow Channels

High current density (> 10 A mm-2) arcs in channels of solid material are determined by (i) arc induced evaporation of wall material, (ii) axial convection, and (iii) radiative energy transfer. Based on these processes, an integral arc model is developed from first principles that relates the arc characteristics to the arc current, the channel geometry, and the properties of the channel material. The model is shown to agree satisfactorily with measurements. For engineering applications approximate scaling laws are derived for the arc field strength, the pressure in the channel and the wall evaporation rate.