Erosion of a Copper Cathode in a Nonstationary Arc Spot. I. Experimental Investigation

Abstract

A study has been made of the dependence of the erosion of a copper cathode of an electric‐arc heater on the basic operating parameters: the arc current, the velocity of movement of an arc spot, and the temperature of the electrode surface. The experiments were conducted in a coaxial electric‐arc heater with a magnetic movement of the arc in an air medium for an arc current of 95–480 A and a magnetic field of 0.005–0.417 T. The duration of the experiment, the axial velocity of a plasma‐forming gas, and the flow rate of a cooling water were held constant. It has been shown that there are two different erosion regimes: the microerosion regime characterized by a weak dependence on the current and the macroerosion regime with a strong dependence on the current; the transition from one regime to the other is realized upon the attainment of the critical value of the current, dependent on the magnetic field and the thermal regime of the electrode. The existence of a velocity interval in which the specific erosion is minimum has been shown, which confirms the predictions of the earlier thermal model of erosion of cold electrodes.