Wafer-level integrated electrospray emitters for a pumpless microthruster system operating in high efficiency ion-mode

Microfabrication, wafer-level integration, and characterization of internally fed arrays of electrospray thrusters for spacecraft propulsion are discussed. 5 μm inner diameter, 100 μm long capillaries and 150-to-300 μm diameter annular extractor electrodes are integrated vertically via a polymer based wafer bonding process, allowing high yield and post testing disassembly of the bonded stack. The small inner diameter of the capillaries allows passive, capillary force driven delivery of the propellant to the emission site, and therefore potentially eliminating the need for an active pump system. The fabricated thruster chips were successfully tested in pumpless liquid delivery configuration under unipolar and bipolar excitation.