Abstract: A multi-functional power supply system for a Hall thruster including a thruster assembly for providing a plasma discharge and a cathode assembly for providing electrons. The cathode assembly includes an emitter, a keeper with a current limiting device, and a heater. A magnetic field source is operatively associated with the cathode assembly for generating a magnetic field to control the discharge. A plasma discharge circuit creates a plasma and accelerates the plasma to produce thrust. A power supply is connected to the keeper and the plasma discharge circuit and is connected to the heater through a switching device responsive to a predetermined condition for interrupting the power to the heater and simultaneously enabling the power supply to deliver power to the keeper and the plasma discharge circuit to initiate production of thrust.

Abstract: A multi-functional power supply system for a Hall thruster including a thruster assembly for providing a plasma discharge and a cathode assembly for providing electrons. The cathode assembly includes an emitter, a keeper with a current limiting device, and a heater. A magnetic field source is operatively associated with the cathode assembly for generating a magnetic field to control the discharge. A plasma discharge circuit creates a plasma and accelerates the plasma to produce thrust. A power supply is connected to the keeper and the plasma discharge circuit and is connected to the heater through a switching device responsive to a predetermined condition for interrupting the power to the heater and simultaneously enabling the power supply to deliver power to the keeper and the plasma discharge circuit to initiate production of thrust.

Abstract: A pulsed Hall thruster system includes a Hall thruster having an electron source, a magnetic circuit, and a discharge chamber; a power processing unit for firing the Hall thruster to generate a discharge; a propellant storage and delivery system for providing propellant to the discharge chamber and a control unit for defining a pulse duration &tgr;<0.1d3&rgr;/{dot over (m)}, where d is the characteristic size of the thruster, &rgr; is the propellant density at standard conditions, and {dot over (m)} is the propellant mass flow rate for operating either the power processing unit to provide to the Hall thruster a power pulse of a pre-selected duration, &tgr;, or operating the propellant storage and delivery system to provide a propellant flow pulse of duration, &tgr;, or providing both as pulses, synchronized to arrive coincidentally at the discharge chamber to enable the Hall thruster to produce a discreet output impulse.

Abstract: A pulsed Hall thruster system includes a Hall thruster having an electron source, a magnetic circuit, and a discharge chamber; a power processing unit for firing the Hall thruster to generate a discharge; a propellant storage and delivery system for providing propellant to the discharge chamber and a control unit for defining a pulse duration &tgr;<0.1d3&rgr;/{dot over (m)}, where d is the characteristic size of the thruster, &rgr; is the propellant density at standard conditions, and {dot over (m)} is the propellant mass flow rate for operating either the power processing unit to provide to the Hall thruster a power pulse of a pre-selected duration, &tgr;, or operating the propellant storage and delivery system to provide a propellant flow pulse of duration, &tgr;, or providing both as pulses, synchronized to arrive coincidentally at the discharge chamber to enable the Hall thruster to produce a discreet output impulse.

Abstract: A tandem Hall field plasma accelerator with closed electron drift includes a magnetic circuit having an inner pole and an outer pole and a magnetic field source and a discharge cavity disposed axially in tandem; the discharge cavity including an axially extending accelerator section defining an exit aperture between the inner and outer poles and a plenum section extending radially outwardly and upstream of the accelerator section and including an anode and a propellant injector. Also disclosed is the use of an electromagnetic coil which provides a magnetic field in a magnetic circuit and includes a multiple turn winding wound on an electrically conductive bobbin. The plasma discharge is connected electrically in series with the electromagnetic coil and a power source with a bobbin defining a single turn secondary coil winding on the magnetic circuit which reduces magnetic field fluctuations in the plasma discharge and reduces eddy currents and consequent heating of the magnetic circuit.

Abstract: A pump for feeding granular material into a pressurized zone having a feed screw (14) located within a cylinder (12). The cylinder is tapered (34) at its discharge end, and the outside diameter of the flights (32) is also tapered (43). The clearance (38) of the tapered flights is significantly greater than the clearance (40) of the non-tapered flights.