Ion thruster having a hollow cathode assembly with an encapsulated heater, and its fabrication

摘要

An ion thruster (20) has a hollow cathode assembly (50) including a heater (72) with an inner ceramic sleeve (52) and an outer ceramic sleeve (58). The outer ceramic sleeve (58) overlies the inner ceramic sleeve (52) with a filament volume (64) between the two sleeves (52, 58). A wound filament (66) has windings disposed within the filament volume (64), and a mass of ceramic powder (68) fills the remaining portion of the filament volume (64) between the windings of the filament (66). A cathode (76) is disposed within the inner ceramic sleeve (52) of the heater (72). The heater (72) is assembled by preparing the filament (66) and forming it into a wound cylinder, and then encapsulating it and the powder between the inner and the outer ceramic sleeves (58). The hollow cathode assembly (50) may serve as a portion of a plasma source (24) or as a portion of a charge neutralizer (40) (Fig. 3).