Next Steps Towards Developing an In-Space IEC Propulsion System

The intent of this work is to directly tie into the effort of leveraging an existing plasma generator based on the Inertial Electrostatic Confinement (IEC) principle from a pure lab device which draws its operating gas from the environment inside a vacuum chamber to a propulsion module with defined gas feed. The IEC devices under investigation create a plasma at pressures typically below 100 mTorr at power levels between 10 and 60 W and generate a confined plasma core from which a rather high energetic beam emanates which is intended to be used for in-space propulsion purposes. The UK approach to these devices of using rectified AC power has still to be established in comparison to the traditional approach of operating IECs with a pure DC voltage. For this purpose, a high voltage power supply will be provided by NASA Glenn to enable a comparison of the two operating modes in terms of operational envelope and efficiency of power delivered to the propulsion system. Geometrically identical designs will be compared based on their electrical characteristics (specifically current and power vs. applied voltage, power contained in the actual IEC beam in reference to provided power) and shape of the beam (tight beam or spray mode) with operating pressure. These characteristics will be supplied with optical diagnostics such as emission spectroscopy and Fabry-Perot interferometry to determine plasma temperatures, composition, and velocity. Beyond application as an electric propulsion system, applications in material sciences for creating thin film coatings of high purity are envisioned with basically the same plasma generator design.