Abstract: Microcathode arc thruster (μCAT) has a good application prospect in micronano satellite space missions, but the life span is an important factor restricting its development at present. An automatic data acquisition system was developed, and the whole life tests at different discharge frequencies were carried out. The morphology changes of cathode materials and conductive films after failure were observed and analyzed. The results show that, at the initial stage of the thruster, the discharge characteristic is an unstable stage, which accounts for less than 10% of the whole life of μCAT. The discharge of thin film resistance is relatively stable in the early stage, which is of the order of several hundred euros, and increases rapidly to the order of thousands of euros when it is close to failure, and the peak current decreases sharply until failure. The increase of discharge frequency makes the heat accumulation in the cathode pit area, enhances the breakage of the conductive film, leads to the early failure of the thruster and reduces the life of the thruster. The uneven distribution of arc ablation position leads to the decrease of cathode utilization, which is an important factor restricting the life of μCAT.

Key words: micro-cathode arc thruster, discharge characteristics, lifetime, ablation, thin film resistance