Impact of Vacuum Facilities on Plasma Thruster Operation

There has been significant investment by NASA, DoD, industry, and private investment to proliferate the flight of high-power electric propulsion (EP) systems. These systems ionize the propellant on the spacecraft and then use electrostatic or electromagnetic forces to accelerate the plasma to create thrust. The thrust is used to maneuver the spacecraft. Unfortunately, as the plasma thruster power level increases, state-of-the-art approaches to correlate ground-test results to in-flight performance and wear are insufficient for the operation of high-power EP devices. This stems from ground-based EP test facilities interacting with plasma thruster operation. The resultant ground-based thruster operation does not represent in-space performance or lifetime. These facility effects include elevated pressure from residual, inadequately pumped gas in the test facility, contaminants from the facility interacting with the thruster, and uncertain electrical paths through the thruster plume and the test facility walls. To enable the flight of high-power plasma thrusters requires a significant advance in our understanding of the fundamental and applied sciences underpinning the impact of background neutral gas on the physics of plasma acceleration, electrical circuits that include the plasma and the vacuum facility, plasma-material interactions, and detailed physics-based models of the plasma ionization, acceleration, and neutralization processes.

This Special Topic presents work from the scientific and technical community that aims to quantify, understand, and predict the physical and chemical impact of ground-based vacuum facilities on plasma thruster operation.