Homogeneous arc ablation behaviors of CuCr cathodes improved by chromic oxide

Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters. In this work, the arc ablation behaviors and mechanisms of commercial CuCr10, CuCr25, and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes. The discharging homogeneity was improved with the increase of chromium content in the cathodes, which was attributed to the formed chromic oxide layer. The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0% compared to the copper cathodes. The chromic oxide formed in the pit protected the bottom matrix, leading to a homogeneous ablation process. The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot. Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.