Modeling of Total Thruster Performance for NASA's Evolutionary Xenon Thruster Ion Optics

Abstract

An axisymmetric ion-optics model is applied to NASA’s Evolutionary Xenon Thruster (NEXT) ion engine. The model is used to simulate the performance of the entire thruster by modeling several apertures at varying radii on the thruster face and integrating the results. The integrated results are compared to experimentally measured data for the NEXT thruster, showing good agreement in most areas. The primary area of discrepancy is in the accelerator grid current, although erosion results suggest that the measured current is unaccountably high. The model is also used to estimate the life of the thruster before the onset of electron backstreaming. Three separate methods are applied, and each predicts thruster failure after approximately 40,000 hours of operation or 845 kg of xenon throughput.