In 2002, NASA GRC was selected by NASA Headquarters Office of Space Science, Solar System Exploration Division, under a competitive NRA to develop high-power electric propulsion for nuclear systems. In 2003, the propulsion technologies unique to nuclear power systems were transferred to NASA's technology initiative under Project Prometheus.

The NASA GRC proposal, High Power Electric Propulsion (HiPEP) is focused on the development of a 20-50 kW class ion thruster with a specific impulse of 6000-9000 seconds, and a propellant throughput capability exceeding 100 kg/kW – with the intent of bringing the thruster to TRL 4-5 within 2 years. The HiPEP team is comprised of GRC, BEDD, Aerojet, Colorado State University, University of Michigan, and University of Wisconsin.

The HiPEP project in June 2003 completed its Phase 1 6- month study effort. During Phase 1: the thruster conceptual design was completed; testing of components were initiated including discharge, neutralizer, and subscale ion optics, and; preliminary full-scale laboratory thruster fabrication is nearing completion. An assessment of the thruster design approach for the JIMO mission was also conducted, indicating it meets all potential requirements.

The thruster approach selected was established based on the critical requirement – life time – which influences all thruster design attributes. All other performance requirements for the thruster have been previously demonstrated in the last 30+ years at NASA GRC using various fidelity thruster hardware (for example, >200 kW operation at > 7,000 seconds specific impulse, in 1967).

The basic design of the thruster is rectangular with an ion extraction plane that will measure approximately 41x 91 cm, which significantly minimizes the current density relative to the SOA. The thruster will generate the discharge plasma via microwave driven electron cyclotron resonance, and extract the beam using pyrolytic graphite grids. Even though the thruster will be designed to operate up to 50 kW, it will be derated to operate at approximately 25 kW. This derated approach greatly improves the likelihood of success and enhances its growth potential for future, higher power applications.

Laboratory model thrusters in Phase 2 will be used as a test bed for evaluating the discharge and ion optics component technologies. Selection of a final design will be completed by the end of Year 1 of Phase 2. Subsequent thrusters will be manufactured by Aerojet which will then undergo detailed performance testing, and a 1000 hour wear test.

Press Releases
 + NASA Successfully Tests Ion Engine