Rarefied Propellant Flow Vector Measurement within a Vacuum Chamber

Abstract

In a ground test facility (vacuum chamber), propellant particles emitted from an electric propulsion thruster are reflected from chamber wall surfaces. They remain within the chamber until evacuation by vacuum pumps. Some particles return to the original thruster. To measure horizontal and vertical rarefied particle flow, a rarefied flow vector detector (RFVD) using an extra-fine thin optical fiber was developed for this study. It was redesigned as described herein. Multi-point measurement results confirmed that both reflection from the chamber wall surface and evacuation using the vacuum pump strongly influence the propellant particle flow. Adequate vacuum pump and thruster locations are discussed for thruster performance evaluation.