Time-spatial structure of an electric arc anode region

Abstract

This paper studies the anode region of an eroding anode with a nonstationary arc-root attachment. High-current free-burning short as well as long arcs at atmospheric pressure are investigated. A technique to study the anode region of the arc is suggested. An anode moving perpendicular to the arc axis was used for estimating parameters of the anode jets at a given moment of their development. The mechanism of current transfer in the anode region is considered on the basis of electrophysical and optical-spectroscopic investigations of the arc attachment traces and plasma parameters both of the anode jet and arc column. The anode jet was found to be of importance in the stationary arc operation. The near-anode plasma parameters depend on the effect of the cathode jet. In short arcs (L/sub a//spl sim/2 mm), the plasma temperature at the anode exceeds 20000 K, while in long arcs (L/sub a/>50 mm), it falls below 7000 K. At plasma temperature T/sub a/>11000 K, the total arc current in the anode region is transferred through the arc plasma, while at lower temperatures, both the arc column and the anode jet take part in the current transfer.