The Onset of the Magnetized Pulsed Vacuum Arc: a Promising Way for High Efficiency Propulsion

Vacuum arcs nowadays are used in the wide range of applications including high current electronics, thin films deposition, particle accelerators and advanced plasma propulsion. Minute vacuum arc thrusters can be attractive for some applications such as small satellites (CubeSats) propelling, and the thrust level of such thrusters can be remarkably enhanced by implementing a magnetic field. However, for such applications as orbit raising or interplanetary missions, the overall performance including thrust and lifetime of such thrusters requires even further enhancement. This can be done by the adding a second acceleration stage to the thruster. Recently, we proposed a possible approach that we called a Micro-Cathode Arc Thruster with Magneto Plasma Dynamical second stage (μCAT-MPD) with applied magnetic field that can be created by either permanent magnet or magnetic coil. The first stage will produce the small shot of plasma, while the second MPD stage will generate even more plasma and accelerate it to the higher velocities by the j x B force. MPD principle of plasma acceleration, in our opinion, prevails over the gridded ion and Hall thruster concepts since it does not require ion-adsorbing and eroding grids, high voltages and cathodes-neutralizers with limited lifetime.Investigating this new plasma thruster, it has been revealed that such a magnetized pulsed two-staged discharge has an onset: its thrust and total charge of expelling ions rapidly jump after certain threshold dc voltage applied to the accelerating (MPD) second stage. Using independent experimental methods, we observed that the mentioned effect allows increasing the thrust (in several tens of times) simultaneously with thrust-to-power ratio (in several times). This opens up the perspectives of creation of new type of miniature and low-power plasma thrusters for small satellites propulsion.