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

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 τ 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.