The NASA Evolutionary Xenon Thruster (NEXT) was a 40 cm diameter ion engine, double the beam extraction area of the NSTAR ion engine. It was developed by the NASA Glenn Research Center as a next generation ion propulsion system in 1998-2003. The NEXT engine followed the derating philosophy used for the NSTAR, and consisted of a stainless steel semi-conic discharge chamber with a ring-cusp magnetic field geometry. Hollow cathodes were employed for electron emission in the discharge chamber and to neutralize the ion beam. The ion optics were dished grids with the same geometries as NSTAR. The engine was designed to be throttled from 1.1-6.1 kW to adjust for varying available power resulting from solar panel degradation over the life of the mission. The NEXT ion engine demonstrated a throttling range of 1.1 - 6.9 kW, specific impulse range of 2210 - 4100 s, with resulting thrust of 50 - 237 mN. The fourth Laboratory Model NEXT engine, referred to as LM4, was built at the NASA GRC with the intention of conducting detailed mappings of the discharge plasma via electrostatic probes and Laser-Induced Fluorescence (LIF). LM4 was completed in October 2003 and transported to PEPL to undergo testing.
Electrical Input Power: 6.90 kW.
Thrust: 0.24 N (0.05 lbf).
Specific impulse: 4,100 s.