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

The liquid material micro-cathode arc thruster (LM-μCAT) is a type of micro-cathode arc thruster (μCAT) 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-μCAT 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-μCAT. The thrust-to-power ratio of Ga-Ti cathode LM-μCAT ranges from 0.32 μN/W to 1.60 μN/W, whereas that of Ga-Al cathode LM-μCAT ranges from 0.42 μN/W to 2.04 μN/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-μCAT can reach 1.75 mN and that of Ga-Ti cathode LM-μCAT is 0.5mN. Since the plasma generated by the Ga-Al cathode LM-μCAT has higher energy, it can lead to higher thrust than Ga-Ti cathode LM-μCAT. At the low current stage, the peak thrust of the Ga-Al cathode LM-μCAT can reach 2.25 mN and that of Ga-Ti cathode LM-μCAT is 0.6 mN. The differences are minimal. In the ablation anode stage, the plasma generated by the Ga-Al cathode LM-μCAT is more than the Ga-Ti cathode LM-μCAT but they have similar ion rates.