Study of a novel ionizer configuration for ion thrusters

Abstract

Micro-satellites often require the adaptation of existing propulsion systems. Electric propulsion thrusters are perhaps the best candidates to meet these needs and ion engines are among the most scalable. Miniaturizing the ion engine will require novel concepts for the ionizer with perhaps novel propellants. MEMS, nanotechnology and other technological advances are expected to impact on new designs. Our work shows that the ionization of Argon, which is an alternate fuel to Xenon, can be achieved at low voltages by utilizing Micro-Structured Electrode (MSE) Arrays. Copper-clad sheets separated by a dielectric material (fiberglass laminate epoxy resin system combined with a glass fabric substrate) of varying thickness (0.1 mm to 0.4 mm) form the discharge electrodes in the MSE arrays The wafers are drilled with an array of holes and this geometry serves to concentrate the electric field between electrodes enhancing electron emission at the cathode. Minimum breakdown voltages between 240 and 280 Volts at pressures of around 100 mTorr (0.133N/m2) were consistently obtained with arrays of hole diameter ranging from 300 to 500um. These results are consistent with conventional Paschen-curves with two empirical constants that arise from our unconventional geometrical arrangements and from the different material properties.