Three-Dimensional Particle-in-Cell Simulations of Bipolar Ionic Electrospray Thruster Plume

Abstract

This paper presents a fully kinetic three-dimensional particle-in-cell (PIC) simulation study of the plume from a bipolar ionic electrospray thruster pair using 1-ethyl-3-methylimidazolium tetrafluoroborate () ionic liquid propellant. The results show a unique beam neutralization process, where there is little physical coupling between the positive cation and negative anion beam. These dynamics are likely attributed to the similar mass ratio between the two beams and the low current density of the beams at this scale. The small potential difference within the beam suggests that low-energy fragmented species will not be significantly scattered, ejected, or likely to return as backflow. The weak electric field magnitude within the beam suggests that the fragmentation of ion clusters within the plume may occur at a reduced rate compared to that measured in laboratory experiments. This implies that ionic electrospray thrusters may offer a relatively smaller contamination risk compared to other micro-electric propulsion devices.