NEXT Study of Thruster Extended-Performance II (NEXT STEP II)

*Ion propulsion technology under NASA’s Evolutionary Xenon Thruster (NEXT) project progresses toward flight application. The existing capabilities of the NEXT xenon ion thruster are reviewed, including previous analyses and test data examining the possibilities of extending the NEXT thruster performance and life time capabilities beyond those demonstrated under the existing program and throttle table. Both high thrust-to-power operation and high thrust density high power operation were evaluated. These analyses were extended here to examine the performance and lifetime implications of increasing the discharge propellant efficiency above those values assumed in the NEXT throttle table. Additionally, enhanced high thrust-to-power operation was examined assuming the use of an improved-perveance ion optics design. Increases in discharge propellant efficiency are projected to provide modest increases in overall thruster efficiency, specific impulse, and thruster service life. Performance estimates for the NEXT thruster with enhanced perveance ion optics indicate thrust-to-power ratios of up to 58 mN/kW are feasible, yielding sub-3000 second specific impulse operation which compares favorably to the BPT-4000 Hall thruster.

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