Three-Dimensional Numerical Simulation of Field-Emission-Electric-Propulsion Neutralization

A three-dimensional full-particle-simulation model is developed for simulation of a e eld-emission-electricpropulsion (FEEP) thruster operation in an ambient plasma. Simulations are performed with ion-to-electron massratios close to actual values (mi/me =80,000)to resolve the basic characteristics of thepropellant ionsemitted from a FEEP thruster and their neutralization in an ambient plasma environment or by a thermionic neutralizer. The slit geometry allows a FEEP emitter to transmit reasonable values of emission current, even when no neutralization mechanism is present. However, to neutralize the FEEP beam, one must either operate the FEEP in an ambient plasma with a density comparable with the density of the FEEP beam ions and/or place a neutralizer at a location sufe cientlyfarfrom theFEEP emitter.Becausetheelectrice eldfrom theexposed high-voltageaccelerator dominates the neighboring region of FEEP thrusters, a neutralizer placed on the spacecraft surface beside the FEEP emitter will not provide effective neutralization.