Liquid metal ion source based on magnetic suspensions for field emission electric propulsion (FEEP)

Abstract

This work presents a process for the creation of emitter structures for liquid metal ion sources based on suspensions of iron and nickel in gallium-based room temperature liquid metal alloys. The process does not require needle etching or vacuum wetting of the emitter. Tip radii of less than 3 μm have been achieved. In addition, first measurements and observations from single emitter emission experiments are presented, including current-voltage characteristics, vacuum stability, degradation mechanisms and first thruster characteristics for the use in field emission electric propulsion. The impedance of the magnetic liquid metal emitters was found to correlate with the mass fraction of particles suspended in the liquid metal. Total impedances up to 30 MΩ have been achieved, indicating the feasibility of emitter clustering. Thrust measurements were performed with a commercial of the shelf load cell and verified in a dedicated setup for field emission electric propulsion testing, featuring a sub micro newton counterbalanced double pendulum thrust balance.