Resilient, Nanostructured, High-Current, and Low-Voltage Neutralizers for Electric Propulsion of Small Spacecraft in Low Earth Orbit

Abstract

We report propellantless neutralizers resilient to oxygen and low-vacuum environments based on arrays of Pt-coated, self-aligned, and gated Si field emitters. These devices emit currents in excess of 1 mA at bias voltages of less than 120 V, adequate for neutralizing the plume of a small spacecraft's electric propulsion system. The reported devices produce similar currents at fivefold less voltage and emitting area than state-of-the-art CNT neutralizers. Long-term (3 hours) continuous emission in a 1 μTorr oxygen partial pressure environment was demonstrated, confirming the compatibility of these neutralizers with low Earth orbit (LEO) conditions. A robust processing sequence was developed that could be employed for high-yield fabrication of large-area field emission neutralizers with active areas larger than 10 cm² for current emission higher than 100 mA.