Particle-Based Plasma Simulations for an Ion EngineDischarge Chamber

Abstract

A particle-based model with a Monte Carlo collision model has been developed to study the plasma inside the discharge chamber of an ion engine. This model tracks five major particle types inside the discharge chamber in detail: xenon neutrals, singly charged xenon ions, doubly charged xenon ions, secondary electrons, and primary electrons. Both electric and magnetic field effects are included in the calculation of the charged particle's motion. The electric fields inside the discharge chamber are computed using a new approach. Also, detailed particle collision mechanisms are enabled. Validation of this computational model has been made on NASA's three-ring Solar Electric Propulsion Technology Application Readiness Program discharge chamber, at the 2.29 kW input power, 1.76 A beam current, and 1100 V beam voltage operating condition. Comparisons of numerical simulation results with experimental measurements are found to have good agreement. The computed ion beam current differs from experiments by 1% and the computed discharge current differs from experiments by 22%. The plasma ion production cost compares within 7% and the beam ion production cost compares within 16% of the experimental values. The overall computed thruster efficiency is found to differ from experiments by 11 %. In addition, steady-state results are given for particle number density distributions, kinetic energy, particle energy loss mechanisms, and current density collected at the chamber walls.