Modeling of a Microscale Short Vacuum Arc for a Space Propulsion Thruster

A model of generation of the plasma supported by the operation of a microscale vacuum arc was developed, considering the phenomena in the cathode and anode spots. The nonequilibrium layers produced by cathode and anode evaporation were studied, and the electrode erosion rates as well as the plasma parameters were calculated. The calculation for 50 A showed that the plasma is dense, with a degree of ionization of about 0.1, and consists of singly charged ions. The anode temperature and erosion rate exceed these parameters for the cathode. It was demonstrated that the relatively large anode erosion rate can cause the larger force in the short vacuum arc compared to the force generated in the long-gap arcs, and this effect should be taken into account when designing a microscale thruster.