Micro Radio-Frequency Ion Propulsion System

TLDR

The LISA mission uses three formation‑flying spacecraft to detect gravitational waves. This paper reports on the development of a 1 cm‑class micro RF ion thruster selected by NASA/JPL to reduce risk for LISA and similar missions. The thruster employs a high‑efficiency RF generator, miniature power processing unit, piezo‑actuated microvalve, and propellantless field‑emission cathode to provide precise propulsion. It delivers 0.1 µN thrust resolution in the 30–150 µN range, consumes about 10 W, and is projected to last over 20,000 hours.

Abstract

The originally planned Laser Interferometer Space Antenna (LISA) mission employs three formationflying spacecraft for the study of cosmic gravitational waves. In order to detect the minute changes in spacetime, the three spacecraft form a triangular constellation with equal arms of five million kilometer each and the separation is precisely maintained by state-of-the-art electric thrusters that offer unprecedented pointing accuracy. As a risk reduction for the LISA mission and for similar future missions, Busek was selected by NASA/JPL to develop 1cm-class micro RF ion thruster system that will provide the essential precision propulsion capability. This paper summarizes the current development of the micro thruster as well as its supporting hardware. Critical subsystem components include an innovative high-efficiency RF generator, a miniature power processing unit, a lightweight piezo-actuated microvalve for propellant management and a propellantless field emission cathode used for ion beam neutralization, all developed by Busek. The micro RF ion thruster has demonstrated 0.1µN-level thrust resolution in the designed 30-150µN operational regime. System power consumption is on the order of 10W. Thruster life, based on grid erosion simulation, is expected to exceed 20,000 hours.