Chromium, a promising cathode candidate for homogeneous arc erosion in air

Abstract Cathode erosion hinders the development of high-power arc heaters, and the inhomogeneous erosion of the copper cathode results in catastrophic failures. In this work, the arc erosion behavior of a chromium cathode was investigated compared with copper. The former was relatively homogeneous with shallow erosion pits. The eroded microstructure suggests that the surface chromic oxide layer could suppress the formation of deep craters. The maximum erosion depth and the erosion rate of chromium were lower than those of copper. The single erosion pits on chromium gradually extended and disappeared, suggesting a reduction in the input energy flux density. The underlying mechanism for the homogeneous erosion behavior of the chromium cathode was proposed. The homogeneous erosion behavior of the chromium cathode makes it a promising candidate for high-power arc heaters.