A Review of Facility Effects on Hall Effect Thrusters

An increasing number and variety of missions are benefiting from Hall Effect Thrusters supplied by different suppliers utilizing a variety of development processes and facilities. This situation, in part, has led to multiple recommendations for standardized approaches in all phases of thruster developments and integration. To help inform such standardization, a review was conducted to collate open-literature data on the measurement and influence of ground test facility pressures on the performance and lifetime evaluations of Hall Effect Thrusters. No flight thrust data were available, so comparisons of ground and in-space thruster performances weren’t possible. The review found that pressures are obtained using a range of approaches which complicate comparisons of pressure effects in different facilities. The limited data base on the influence of pressure on thruster performance exhibited extreme variations and recent, non-invasive diagnostics efforts both provide new physical insights into the interaction of facility environments with thrusters and indicate the use of simple, ingestion correction factors are inadequate. Few data were found that directly evaluated the influence of pressure on thruster lifetime and the cited non-invasive diagnostics studies suggest that effects other than partial pressures of contaminants may be critical. No data on facility effects on swirl torques were found. Overall, the review illustrated the extremely situational nature of the effects of facility pressure and strongly supports the establishment of test standards for Hall Effect Thruster programs.