微阴极电弧推力器平板电极放电特性实验研究

Micro-cathode arc thruster （μCAT） has the advantages of high specific impulse，small impulse bit and simple structure，and has broad application prospects in micro-nano satellite missions. In practical application，with the increase of ignition times of thruster，the degradation of the conductive coating continues to intensify. This leads to the performance degradation or even failure of thruster，which becomes a key factor limiting the further development of thruster application. In this paper，the experimental study on the discharge characteristics and failure mechanism of micro-cathode arc thruster was carried out with a plate electrode structure. The results show that the evolution of the arc distribution formed by the discharge between electrodes can be divided into four stages in the whole life cycle： concentrated，diffused，dispersed and near failure discharge stages. The main factors that dominate the change of discharge characteristics are cathode ablation and coating degradation. When the thruster is close to failure，the arc voltage increases significantly，the arc current decreases significantly，the discharge time is further shortened，and the resistance between electrodes increases sharply，which inhibits the generation and development of micro-cathode arc. Under the experimental conditions of this paper，when the ignition times reached 6.9×10⁵，the thruster failed. At this time，the resistance between the anode and cathode increased sharply to 153kΩ. The analysis of the temporal and spatial evolution of the discharge characteristics under vacuum conditions will help to clarify the failure mechanism of the thruster and provide a basis for improving the life and performance of the thruster.