Design and characteristic analysis of micro-cathode arc thruster using liquid metal as working medium

Abstract

The limitation associated with the application of titanium micro-cathode arc thruster (Ti-μCAT) is that the cathode working medium carried in a single space mission is insufficient. To address this issue, a μCAT using liquid metal as the working medium (LM-μCAT) was designed. The discharge characteristics and performance parameters of the LM-μCAT and Ti-μCAT were examined. The experimental results show that the LM-μCAT has higher elementary impulse, lower ion velocity, higher plasma ionization degree, and lower power consumption. Theoretical analysis indicates that the differences are caused by the surface structure and physical property parameters of the two working media. The reason for the change of elementary impulse and ion velocity is the larger average atomic mass of liquid metal. The discrepancies in plasma ionization degree and power consumption are caused by the difference between the energy proportion of metal into metal vapour and ionized metal vapour to form plasma. The change in the energy proportion is caused by the physical characteristics of the cathode and the roughness of its surface.