Abstract: An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

Abstract: An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

Abstract: A CROSSATRON plasma switch has a peak current capability in excess of 10kA and a switching speed of at least 1.times.10.sup.11 A/sec, making it compatible with the requirements of excimer and CO.sub.2 gas laser switches, and yet is small enough to be mechanically integrated with such lasers. It employs an axially corrugated cathode with a body diameter on the order of 10 cm and shallow corrugations whose depths are about 1.0-1.5 times the distance between corrugations, together with a reduced diameter anode (of about 2.5 cm diameter for an excimer laser and about 1.25 cm diameter for a CO.sub.2 laser), to obtain a plasma volume of about 50-100 cm.sup.3 for rapid switching. A magnet assembly around the cathode uses only two stacked magnets, but has an overall greater axial length and surface magnetic strength than in prior switches. The magnet design produces a high field strength near the cathode, but without a significant extension of the field into the anode region.

Abstract: A CROSSATRON switch is capable of operating with voltages in excess of 100 kV by the use of a deuterium gas fill to increase the Paschen breakdown voltage, axial molybdenum cathode corrugations to provide a higher current capability, and a Paschen shield that is formed from molybdenum. The terminal curvature of the Paschen shield and of the adjacent portion of the anode are selected to establish a voltage stress at the curved Paschen shield surface within the approximate range of 90-150 kV/cm in response to a 100 kV differential.