Performance improvement of a dual-anode liquid-metal micro-cathode arc thruster through delayed alternating triggering of two anodes

The liquid-metal micro-cathode arc thruster (LM-μCAT) operates in a pulsed mode and features a simple structure, high specific impulse, and low energy consumption, making it a promising propulsion device for microsatellites and nanosatellites. However, its relatively low elemental impulse limits its practical applications. In this study, a dual-anode LM-μCAT was developed to operate under a delayed alternating discharge mode. Compared with the conventional single-anode μCAT operating in a single-pulse mode, this operating mode effectively increases the elemental impulse of the μCAT. By alternately triggering two anodes with a common cathode, the plasma ionization process is enhanced and the elemental impulse is increased without a substantial rise in energy consumption. Experimental results show that, as the trigger delay of the second anode relative to the first anode increases, the elemental impulse first increases and then decreases. The maximum elemental impulse is obtained at a delay time of 20μs, at which the peak arc current and plasma ionization level also reach their highest values. In contrast, the maximum thrust-to-power ratio is achieved at a delay time of 80μs. This result indicates that delayed alternating discharge not only enhances thrust-related performance, but also improves energy utilization efficiency. The improvement is attributed to an auxiliary ignition effect, in which the plasma generated after ignition between the earlier-triggered anode and the common cathode facilitates the subsequent ionization of the later-triggered anode with the same common cathode. These results demonstrate that delayed alternating discharge is an effective operating mode for improving the overall performance of the LM-μCAT.