Advancing the thrust-to-power ratio of the liquid metal micro-cathode arc thruster: the effect of the different cathode material

Abstract The liquid material micro-cathode arc thruster (LM- μ CAT) is a type of micro-cathode arc thruster ( μ CAT) with liquid cathode at room temperature. It can feed a number of cathode materials theoretically in a single space mission. The performance differences of LM- μ CAT with different cathode materials are compared in this study. The material is a mixture of gallium (Ga) with either aluminum particles (Ga–Al cathode) or titanium particles (Ga–Ti cathode). Results show that the particle size has no effect on the LM- μ CAT. The thrust-to-power ratio of Ga–Ti cathode LM- μ CAT ranges from 0.32 μ N/W to 1.60 μ N/W, whereas that of Ga–Al cathode LM- μ CAT ranges from 0.42 μ N/W to 2.04 μ N/W, which increases by about 34%. The discharge process is divided into three stages: high arc current stage, low current stage, ablation anode stage. Differences in the thrust-to-power ratio are attributed to the high arc current stage and ablation anode stage. At the high arc current stage, the peak thrust of the Ga–Al cathode LM- μ CAT can reach 1.75 mN and that of Ga–Ti cathode LM- μ CAT is 0.5mN. Since the plasma generated by the Ga–Al cathode LM- μ CAT has higher energy, it can lead to higher thrust than Ga–Ti cathode LM- μ CAT. At the low current stage, the peak thrust of the Ga–Al cathode LM- μ CAT can reach 2.25 mN and that of Ga–Ti cathode LM- μ CAT is 0.6 mN. The differences are minimal. In the ablation anode stage, the plasma generated by the Ga–Al cathode LM- μ CAT is more than the Ga–Ti cathode LM- μ CAT but they have similar ion rates.