A field-
ionization based electrical
ion thruster utilizes a single
propellant that can be used in either a high specific-impulse mode, i.e.,
ion-thruster mode, or a low-specific-impulse mode, i.e., a cold-gas thruster mode. In one embodiment, the high
specific impulse mode (
ion thruster mode) utilizes a miniaturized positive-ion field-
ionization chamber including a permeable substrate infused with properly oriented carbon nanotubes (CNTs), which is fed
propellant from a porous injection plug made from permeable carbon or equivalent material. In one embodiment, field-
electron emission from a neutralizer, such as a
carbon nanotube array neutralizer, positioned after one or more accelerator grids is used for ion
neutralization. In one embodiment, the low specific-impulse (cold-gas mode) uses a conventional
supersonic nozzle-expansion to generate thrust. In one embodiment, both the high specific-impulse mode and the low specific-impulse mode thruster embodiments share the same gas
propellant, storage
propellant tank, and delivery equipment.