A Summary of the NEXT-C Flight Thruster Proto-flight Testing

Aerojet Rocketdyne (AR), under contract to NASA Glenn Research Center, built, tested
and delivered the first flight version of the NEXT-C (NASA Evolutionary Xenon Thruster –
Commercial) engine system. This system is comprised of a 7 kW thruster and power
processing unit which are the commercial variants of the NEXT prototype thruster and power
processing unit. In addition to developing the NEXT-C engine system for potential future
NASA science missions, AR is dedicated to ensuring that this propulsion system is viable for
commercial users and a wider variety of commercial applications.

This paper will focus on the performance of the first flight model thruster, SN001, and
presents an overview of the proto-flight testing environments and data obtained. For this first
flight thruster, the proto-flight test sequence involved characterizing the performance of the
thruster, in addition to vibration and thermal vacuum testing of the thruster. Between each
of these environmental tests, the performance of the thruster was verified, ensuring that the
environmental exposures, i.e. vibration and TVAC, did not affect the thruster performance.
Specifically, the proto-flight data obtained included discharge chamber, optics and neutralizer
performance. Faraday probe and ExB data obtained in the regions downstream of the
thruster are presented and used to calculate thrust, and therefore specific impulse and total
efficiency. Lastly, data are presented showing how the centroid of the ion beam, assumed to
be indicative of the thrust vector location, varies throughout the entire proto-flight test
campaign.

The proto-flight testing of the NEXT-C PPU is documented in a previously published
paper by Bontempo4. Following the proto-flight testing of the thruster, the thruster and its
PPU successfully completed a System Integrated Test (SIT) tailored to the DART Mission.
After the completion of the proto-flight testing, the SN001 thruster and SN002 PPU were
delivered to APL for use on the DART mission.