Investigation of the Positive Column of High-Current Metal-Vapor Arcs

Abstract

An analysis of the positive column of a high-current metal-vapor arc in a vacuum atmosphere is presented. Data for the analysis was obtained from the voltage-current characteristics of 60-Hz vacuum arcs with copper electrodes. Results of the analysis show that, for arcs carrying currents greater than 8000 amperes rms, the dominant mechanisms for controlling the size and transport properties of the arc column are magnetic pinch force and radiation energy losses. For arcs with currents ranging between 8000 and 26 000 amperes rms, the temperature, metal-vapor density, and electrical conductivity range from 9000 to 20 000°K, from 7.4 X 1016 to 1.1 X 1018 cm-3, and from 3.3 X 103 to 1.3 X 104 mho/m, respectively. Also, the time dependent on these quantities during an ac arc is presented.