Description: In Phase I Busek matured the design of an existing 15-kW laboratory thruster. Magnetic modeling was performed to generate a circuit incorporating magnetic shielding. Erosion modeling predicts extremely long lifetime and high throughput. A detailed mechanical design of the thruster resulted in an overall assembly with specific mass <3kg/kW. Modal, dynamic and thermal analyses were performed to calculate resonance frequencies, mode shapes, stress and fatigue values and temperature limits. Experiments using the existing laboratory thruster evaluated a modified anode/gas distributor and a B-field distribution representative of the proposed magnetic shielded configuration. Performance results suggest similar efficiency and performance as the baseline thruster. Visual observation of the plume illustrated the characteristics of magnetic shielding were achieved. In Phase II Busek will complete the detailed design of the thruster and a center mounted hollow cathode. A prototype unit will be fabricated and performance tested included limited duration testing at Busek. Depending on facility availability the thruster will independently tested at GRC. Busek will hold a MRR and CDR then fabricate, assemble, and fully test a qualification model thruster/cathode to raise the maturity to TRL 6. The thruster will be delivered to NASA for extended duration testing to complete the qualification.

Benefits: NASA has identified 30kW-class SEP systems as a high-value intermediate step towards higher power systems due to broad cross-cutting capability. Current NASA investments include advanced next-generation solar arrays and higher power electric propulsion technologies to enable 30kW-class SEP. The ESPA ring is one approach being considered for partner-based mission concepts and those capable of being launched as secondary payloads. In addition NASA is investing in EP development of 15kW class HET system using either direct-drive and/or high voltage power processing unit. The possibility for using Hall thrusters for lunar and Mars missions has also been well investigated.

A 15kW thruster with throttle ability to 5kW has applications on DoD and commercial ComSats. Hall thrusters could enhance many high power DoD and commercial missions such as satellite servicing, orbit maintenance, orbit raising and lowering, inclination changes, and repositioning. The system could also find near term application on an all-electric upper stage derived from Busek's ESPA orbit maneuvering system (OMS), a free flying S/C based on the ESPA ring. The high power (30kW) version would be used for transportation of propellant to a LaGrange positioned fuel depot.