High Current Cathode Development

High power dual mode Hall effect thruster system is an enabling technology for the orbital transport of DoD and commercial space assets. A dual mode Hall thruster is a propulsion system that is capable of efficient operation in a high thrust to power mode as well as a high specific impulse mode. This places not only stringent demands on the operating range of the thruster and power processor but also the hollow cathode used as the electron source for the thruster. In Phase I, Busek designed, fabricated and tested candidate high current cathode designs. Two designs demonstrated sustained operation at emission currents greater than 200 amps. One of the cathodes was tested for 100 hours of continuous operation at 110 amps. This cathode design was modeled using L-3 (formerly Boeing EDD) proprietary model and a first order lifetime prediction of 25,000 hours was estimated. In Phase II, additional characterization testing of various candidate designs will be performed. Demonstration of the 10 to 1 current turn-down range and lifetime will be a key objectives of the Phase II activities. Toward the conclusion of Phase II an advanced engineering model prototype will be fabricated and a 1000 hour test performed at high sustained current. A system design with Busek’s dual mode HET and modular PPU will be generated to serve as the basis for an integrated system demonstration test. An engineering prototype cathode will be delivered to the Air Force.