Improvement of Microcathode Arc Thruster Lifetime by Deposition of Boron-Containing Coating

Boron-containing coatings are actively used to improve the surface properties of mechanical parts of various devices and cutting tools. In this Paper, we demonstrate that deposition of boron-containing coatings by direct electron-beam evaporation of a boron target with a fore-vacuum plasma-cathode electron source can be used to substantially (by a factor of approximately 6–17) improve the lifetime of miniature (centimeter-sized), low-power (several watts), micronewton thrust level microcathode arc thrusters. Such improvement is a result of slowing down the interelectrode film degradation that occurs after numerous arc pulses. This improvement is observed after applying a hard (resistant to shock by plasma in a single pulse) sputter-resistant (able to maintain its protective properties for numerous pulses) boron coating on the interelectrode dielectric (alumina ceramic). This finding opens up a new way to improve the performance and lifetime of low-power vacuum-arc based propulsion devices for small satellites.