Three‐dimensional electromagnetic thermal fluid simulation of re‐strike phenomenon in magnetically driven arc between parallel electrodes with edges

Abstract

A magnetically driven arc does not advance smoothly between parallel electrodes with edges. The anode spot stagnates on the anode surface when the arc column and cathode spot move forward. According to experimental results, when the arc column moves closer to the anode surface, or a high‐temperature gas comes into contact with the anode, a new anode spot appears and electrical breakdown occurs. Meanwhile, the original anode spot disappears. It is well known as the re‐strike phenomenon. Also, it can be observed using a bandpass filter (520 nm) that a large amount of Cu vapor is generated whenever a new anode spot appears. Because the Cu vapor considerably increases the arc's radiative emission and has a dissimilar effect on the gas's electrical conductivity at different concentrations, a three‐dimensional electromagnetic thermal fluid simulation program that considers the metal vapor from the electrodes is proposed in this paper. Based on the experimental figures, it is able to simulate the re‐strike process by controlling the electrical conductivity of the control volume at the anode surface. In addition, the physical properties of the arc plasma, the original anode spot area, and the re‐strike point area are analyzed, in order to elucidate the occurrence conditions of the re‐strike phenomenon. The results show that the arc form is affected by the electrode jets, which leads to an increase in the electric field density between the re‐strike point and the arc column, thereby causing the re‐strike phenomenon to occur. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.