Bimodal Bismuth Vapor Hall Thruster

Busek is developing bismuth vapor Hall thruster systems for bimodal and high thrust missions. In Phase I, Busek designed and analyzed a bismuth thruster system. An extensive series of experiments led to a pressure regulated liquid bismuth feed system design. Bismuth will be stored as a compact solid on the spacecraft. Most significant feed system elements were tested. Numerical modeling showed the bismuth discharge to be highly efficient; bismuth thrusters will outperform similar xenon thrusters. Maximum thrust to power (T/P) and thrust to system mass (T/M) will both increase substantially. Bimodal capabilities benefit; high T/P is possible throughout the range 1000 sec < Isp < 3000 sec. The tenuous bismuth charge exchange plasma leads to less thruster erosion than observed in a xenon system; this means high total impulse (longer lifetime), and helps mitigate spacecraft interactions, which were scoped out by Aerospace Corporation under subcontract. In Phase II, Busek will design, and build a complete bismuth Hall thruster system. Performance and plume testing will lead to an optimized, deliverable prototype system. A cooled beam condenser will facilitate testing in modest facilities. Busek will also design a full-scale thruster to be built in a follow-on program.