Research on the Ablation of Multiple Alloy Electrodes under the Effect Hundreds Ka Pulsed ARC

Abstract

Air gap serves as the pivotal unit for the current conduction and arc interruption of gas gap switches. The pulsed current conducts energy through the arc plasma in the air gap, forming an instantaneous power deposition in the air gap. Different from the electrical contact in hundred-ampere-level, when the maximum power of the load device reaches up to several GW, and the peak current increases to hundreds of kiloampere, the “thermal erosion” and “shock force” of the arc plasma in the air gap are significantly enhanced. The high-energy arc plasma damages the electrode surface, and causes it to be eroded, sublimated, and sputtered. This study introduces the damage characteristics of different alloy materials under arc plasma. The extreme discharge condition with the peak current of 100kA is set. Compare the surface ablation of the cathode and anode in four commonly used electrode materials: tungsten copper, chromium copper, alloy steel, and aluminum oxide dispersion strengthened copper alloys (ODSC). The results show that the “fluidized” phenomenon is most obvious in ODSC, which is closely related to the shock wave of the plasma boundary. At the same time, the average mass loss of ODSC is also the largest. On the contrary, the tungsten copper electrode has the most uniform ablation on the macroscopic appearance. In regard to roughness of the surface. The alloy steel is in a “semi-spattered” state under the thermodynamic effect of the plasma with the current of 100 kA, that is, the metal droplets adhere to the electrode surface in a detached manner from the SEM result, t, making the roughness extremely large. The relative mass loss rate of chromium copper is the same as that of tungsten copper. However, due to the higher density, the absolute mass loss is slightly larger than that of tungsten copper electrode. Combined with the thermodynamic analysis of plasma under the condition of pulsed current, for 100kA pulsed arc, alloy steel and ODSC have some disadvantages in melting characteristics, but the performance of tungsten copper alloy is relatively stable. If the current further increases, chromium copper alloys may have greater potential.