Towards independent thrust and specific impulse control in a three-stage µCAT-MPD thruster

Space has been becoming increasingly more commercialized and, as a result, more accessible. Higher demand and technological advancement has driven this expansion and lead to the standardization of low-formfactor satellites, CubeSats. These small systems can provide various services, ranging from GPS and network-building to Earth remote-sensing and weather-monitoring. Unfortunately, the operational time of these satellites is significantly limited by their ability to perform station-keeping maneuvers for long periods of time. Small electric propulsion systems, with their low complexity and high impulse, are a promising solution to this problem. In this work we experimentally investigate performance characteristics (ion velocity and thrust) of the laboratory model of novel three-stage configuration of micro-cathode arc thruster (µCAT) small propulsion system for CubeSats. We found that depending on the voltage on the second stage, ion velocity can grow (from 8 to around 20 km/s) with the third-stage voltage, while the maximal thrust values (more than 1 mN) are achieved at the maximal (120 V) positive voltages on both stages. These findings represent the next step towards controllable multimodality of the low-power vacuum arc thrusters for micro-satellites.