Study on Variation and Movement of Extraction-Ion Beam by Grid Wear in Miniature Ion Engines

抄録

This paper focuses on the variation in extraction-ion beam performances in miniature ion engines due to grid erosion. Because speed and cost are very important issues in microspacecraft development, we replace time-consuming grid wear tests with numerical simulations using the JAXA Ion Engine Development Initiatives (JIEDI) tool. By comparing the results obtained for a miniature ion engine with those of a μ10 ion engine, we observe significant extraction-ion beam performance degradation in the miniature ion engine. Because miniature ion engines tend to omit gimballing devices to save their masses, we also present a numerical simulation for predicting erosion-induced movement in the thrust-vector direction for the estimation of the accumulation of thrust-vector misalignment toque, which must be unloaded by firing low-Isp chemical thrusters. Using the JIEDI tool, we can successfully calculate its movement by grid erosion and obtain the averaged thrust-vector direction during the operation of the ion engine. This time-averaged thrust-vector direction provides the best initial thruster setting angle for each miniature ion engine.