Emissive Ion Thruster -EMIT

A propulsion system is proposed that is based on acceleration of ions emitted from a thin, solid-state electrochemical ceramic membrane. This technology would provide a versatile propulsion system that would be suitable for long-term, low-thrust missions throughout the deep-space to near-Earth range. The specially formulated and fabricated membrane in combination with an applied bias voltage will be used to ionize propellant electrolytically and selectively pass ions from the membrane through an ion acceleration stage thereby producing an energetic ion beam and generating thrust. Previously, electrostatic ion propulsion systems have used ion production mechanisms based on electron bombardment ionization, contact ionization, or direct ion extraction from field emission structures. In contrast, ceramic membranes operate at modest temperatures and are theoretically capable of forming ions at ion energy costs that approach dissociation energies (e.g., ~1-2 eV/ion). In addition to being readily scalable to larger sizes, the ion flux through the ceramic membranes is easily controlled over large ranges and this enables deep throttling capabilities. Ceramic membranes are rugged and insensitive to contamination from atmospheric gases, and they have displayed very long lifetimes in similar applications. Furthermore, ceramic membranes do not require the high voltages associated with field emission schemes.