Physics of Cathode Phenomena in a Vacuum Arc With Respect to a Plasma Thruster Application

Abstract

The local cathode heating, vaporization, electron emission, cathode sheath, and so on were considered taking into account the kinetics of mass flow at the vaporized cathode surface. A self-consistent model was developed and simulation was conducted for given spot current $I$ to obtain the cathode erosion rate $G$ and jet velocity $V$ determined the force on the cathode. The time-dependent cathode and plasma characteristics were calculated for Cu, Ag, Al, and W cathodes. The primary plasma needed to initiate the spot was taken into account. Various primary plasma parameters were defined by different spot ignition time $\tau$ at which then the spot can be developed. The model shows that the time-dependent range of $G$ agrees well with the measured data and the jet velocity $V$ calculated from the experimental data of cathode force also close to that velocity obtained experimentally in a literature. The trust performance was obtained larger for W cathode than that for Cu and Ag cathodes and this and other results were discussed.