Effect of The Distance Between the First and Second Stages on the Performance of the Micro-Cathode Arc Thruster with Mpd Second Stage

Addition of the second magneto-plasma-dynamical (MPD) stage allows significant increase of the thrust, the thrust-to-power ratio (TPR) and the efficiency of the micro-cathode arc thruster (μCAT) [1] . Previously, we studied the effect of the magnetic field source and configuration, and the shape of the second-stage electrode on the performance of the μCAT-MPD thruster [1] - [3] . Since the second-stage electrode is the main factor in the onset of the vacuum arc leading to the performance improvement [1] , it seems that the distance between the two stages of the μCAT-MPD thruster is an important parameter that impacts the physical processes. Here, we demonstrate that on the two-stage μCAT-MPD thruster, an optimal distance exists at which the thruster produces a high milli-newton thrust at high TPR and efficiency. Higher distance leads to an increased threshold voltage required for the onset of the second stage, which deteriorates the thruster’s performance, while the zero distance between the stages (in this case the MPD electrode becomes the part of the anode of the first stage) allows achieving only the moderate improvement of thrust level without any possibility to throttle it.

Addition of the second magneto-plasma-dynamical (MPD) stage allows significant increase of the thrust, the thrust-to-power ratio (TPR) and the efficiency of the micro-cathode arc thruster (μCAT) [1]. Previously, we studied the effect of the magnetic field source and configuration, and the shape of the second-stage electrode on the performance of the μCAT-MPD thruster [1]- [3]. Since the second-stage electrode is the main factor in the onset of the vacuum arc leading to the performance improvement [1], it seems that the distance between the two stages of the μCAT-MPD thruster is an important parameter that impacts the physical processes. Here, we demonstrate that on the two-stage μCAT-MPD thruster, an optimal distance exists at which the thruster produces a high milli-newton thrust at high TPR and efficiency. Higher distance leads to an increased threshold voltage required for the onset of the second stage, which deteriorates the thruster’s performance, while the zero distance between the stages (in this case the MPD electrode becomes the part of the anode of the first stage) allows achieving only the moderate improvement of thrust level without any possibility to throttle it.