Wide Throttling, High Throughput Hall Thruster for Science and Exploration Missions

In response to Topic S3.04 "Propulsion Systems," Busek proposes to develop a high throughput Hall effect thruster with a nominal peak power of 1-kW and wide throttling range in terms of both power and Isp. In Phase I, we will design the thruster, focusing on achieving a magnetic field that shields the discharge channel from ion induced erosion. Our goal is to achieve a propellant throughput of at least 100 kg per kW of input power and a system specific mass of 6 kg per kW. Numerical modeling will play an important role in the thruster design to achieve these lifetime targets. Erosion predictions will be validated by comparing model results to measurements taken in a nominal 600 W thruster during an accelerated lifetime test scheduled take place in 2011 at NASA GRC under separate funding. In Phase II, we build and test a laboratory model thruster capturing the essential magnetic field criteria. The performance, lifetime, and plume properties of the thruster will then be evaluated, and the design will be optimized. Our goal is to reach TRL 5 by the end of Phase II. The complete flight system built in Phase III will include a high power thruster, a hollow cathode, and a propellant feed system. However, the focus of this program will be the thruster.

The proposed system has many applications both as a stand-alone system and as part of a much larger (higher power) cluster. On its own, the thruster will be well suited for orbit raising and interplanetary transfers, supporting exploration and science missions. The demonstrated throttling ability is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. Mars orbits at 1.52 AU, which reduces the solar constant to 43% of the value at Earth. Venus orbits at 0.72 AU, which increases the solar constant to 190% of the value at Earth. As a result the output power of a nominal 600 W array varies between 260 W and 1.15 kW as a spacecraft travels between these planets. The ability to throttle efficiently is even more important for missions beyond Mars. The thruster may also be used for orbit raising and circularization (including GTO to GEO transfers) and inclination changes. In GEO, the thruster may be used for station-keeping and repositioning. On its own, the thruster is well sized for primary propulsion on ESPA-sized spacecraft (~180 kg). Clustered, the thruster will support larger, higher power spacecraft and systems, such as a small electric upper stage.

Commercial applications for the proposed system include orbit raising, circularization, inclination changes, repositioning, and station-keeping. For higher power missions, the system would be clustered. Commercial applications for a clustered system include a small electric upper-stage. Other applications include a system for de-orbiting spacecraft that have reached their end of life.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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