Experimental investigation on discharge degradation characteristics for micro-cathode arc thruster

Micro-cathode arc thruster (μ-CAT) is a new type of micro-thruster developed recently. It uses vacuum arc to ablate the cathode material to form a plasma to generate thrust. During the working process, the discharge characteristics of thruster show obvious changes. And they help to reveal the physical mechanisms about thruster. In this paper, the life ignition test of the micro-cathode arc thruster was carried out with the operating frequency of 20Hz. We obtained the variation law of the breakdown voltage and discharge peak current of the thruster, and the ablation of the conductive film after work is analyzed. The research results show that the full lifetime of micro-cathode arc thruster can be divided into the initial stage, stable stage and failure stage. The breakdown voltage and discharge peak current change greatly in the beginning and then have smooth variations. When it closes to failure, the peak current of the discharge decreases rapidly. Therefore, the peak discharge current can be selected as the criterion for the failure of the thruster. After the experiment, it is found that the conductive film does not form uniform ablation, which is the main factor limiting the lifetime of the thruster.