Plume Focusing in Grid-Enhanced Vacuum Arc Thruster Under Magnetic Nozzle

A vacuum arc thruster (VAT) exhibits significant potential for aerospace applications due to its robust structure and high specific impulse. The use of magnetic nozzles can enhance the performance. In this study, a grid-enhanced VAT with axial discharge was designed, and a magnetic field aligned with the discharge direction was applied for investigation. Results indicate that the electron temperature at the cathode spot and the plume region exhibits opposing trends. An electron cooling zone is observed approximately 40 mm downstream of the cathode, where the electron temperature decreases by up to 50%, corresponding to a 160.3% increase in plasma density and a 47% increase in ion velocity. Measurements of beam deposition reveal that the application of the magnetic field reduces lateral deposition by 77.2%, indicating that film replenishment primarily originates from low-velocity metal vapor and that a phenomenon of ion scattering through the grid was also observed. The rate of thrust increase diminishes with stronger magnetic fields, which is attributed to the suppression of the plume density by excessively strong magnetic fields, with an optimal magnetic field determined to be 190 G.