Abstract: An assembly of a Ta inner conductor (20) and a Ta outer sheath (22 or 22?) has an intermediate layer (24) of fused grain alumina or aluminum nitride insulation material. The assembly is swaged and wound to form a helical coil of several wraps. Individual wraps can be of square or rectangular cross-section.

Abstract: A system for uniformly distributing propellant gas in a Hall-effect thruster (10) (HET) includes an anode (42, 42′) and a porous material gas distributor (60, 89) (PMGD). The porous material (120) may be porous metal or porous ceramic. Propellant gas is directed from a supply to the PMGD for distribution into a gas discharge region (16) of the HET (10). The gas flows through the porous material (120) of the PMGD and out of the PMGD's exit surface (71) into the annular gas discharge region (16). The PMGD has an average pore size, pore density and thickness that are optimized to control the flow of the gas at the desired flow rate and distribution uniformity at a relatively short distance downstream from the PMGD. This feature allows HET to be short, significantly decreasing susceptibility to vibration problems encountered during vehicle launch. The PMGD can include a shield (79, 80) for preventing contaminants from traveling upstream from the gas discharge region from adhering to the porous metal.

Abstract: A specially designed magnetic shunt is provided encircling the anode region and/or annular gas distribution area of an ion accelerator with closed electron drift. The magnetic shunt is constructed to concentrate the magnetic field at the ion exit end, such that the location of maximum magnetic field strength is located downstream from the inner and outer magnetic poles of the accelerator. The specially designed shunt also results in desired curvatures of magnetic field lines upstream of the line of maximum magnetic field strength, to achieve a focusing effect for increasing the life and efficiency of accelerator.