Apparatus for study of ion-thruster propellant ionization

Abstract

Electric propulsion thrusters are considered to be candidates for microsatellites; ion engines are among the most scalable. Miniaturizing the ion engine will require novel concepts for the ionizer. MEMS, nanotechnology and other new technologies are expected to impact here. This thesis explores the use of these technologies to enable a new design for ion-thruster propellant ionization. An ideal approach, using expensive fabrication processes, is first described. This approach could prove to be a good method for testing and for the collection of precise data. A cost effective approach, on which our testing is based, is then discussed in detailed. After assembling a facility which uses existing vacuum systems and available instrumentation, we manufactured and tested miniature discharge geometries consisting of commercial 2â x2â copper-clad wafers. Three nominal insulator thicknessâ were used, 0.005,â 0.010â and 0.115.â The wafers were each drilled with 9 equal wholes of diameters 300, 400, and 500 m. A total of 12 wafers were tested (including 3 widths without wholes for a baseline) for the breakdown voltage as a function of argon pressure in the range of 10 to 1000 mTorr. Results indicate that argon breakdown may occur in the holes consistent with the classical Paschen curves.