Abstract: A gas ionizable to produce a plasma is introduced into a channel within an ion source and into a hollow cathode embedded within the same ion source. A combined anode and manifold is located at a closed end of the channel and gas is introduced into the channel through the combined anode and manifold and into the hollow cathode. A heater and keeper electrode power supply is used to establish a hollow cathode and keeper electrode plasma. A discharge power supply is used to flow electrons from the hollow cathode in a predominately 180.degree. direction to bombard the channel gas distribution and create a channel discharge plasma. A magnetic field generated by a permanent magnet circuit is concentrated by pole pieces at the open end of the channel in an orientation predominately transverse to the channel axis. Energetic electrons from the hollow cathode interact with the concentrated field to simultaneously ionize the channel gas and accelerates these ions through the open channel to form an ion beam.

Abstract: A gas ionizable to produce a plasma is introduced into an arcjet whose design includes integration of performance enhancing components in a complimentary manner to significantly improve arcjet performance and capabilities. Major integrated design features include an energy recovery chamber, heat exchanger and by-pass gas flow system which enable the integrated arcjet to operate with minimal frozen flow energy losses, high specific powers and very high thrust levels.

Abstract: A gas ionizable to produce a plasma is introduced into a arc head and a plasma discharge is initiated at voltages less than 50 V between a high resistance helix, impregnated with low work function materials, within the arc head, and a downstream arc channel electrode. Plasma from this discharge migrates into a gap between the arc channel electrode and a weld work piece creating a conducting path adequate to draw a high current arc column from the arc head to the weld work piece at arc initiation voltages less than 50 V. Increased energy density and penetration of the melt zone at the weld work piece is enabled by a predominately axial magnetic field around the arc column, with other magnetic fields enabling manipulation of the arc column over the weld work piece. Further manipulation of the arc head plasma discharge allows a vigorous metal vapor deposition process to be performed which can be sustained simultaneously with a welding operation.