Numerical Investigation of Steady and Transient Ion Beam Extraction Mechanisms for Electrospray Thrusters

Electrospray thrusters are simple propulsion systems, which can be operated on nanosatellites, and it is possible to reduce components of high pressure gas systems using ionic liquid as a propellant. However, evaluations of electrospray thrusters are difficult in experiments since the size of emitter cones is on the order of micrometers. Then, the authors performed Particle-in-Cell simulations of ions in the electrospray thruster and investigated ion beam extraction mechanisms in steady and transient flows numerically. The simulation results show that steady ion beam distributions were rarely affected by ion species. On the other hand, it was clarified that a jet affected the ion beam profiles. In addition, the authors evaluated propulsion performance of the electrospray thruster, which showed a thrust of about 64 nN per emitter and a specific impulse of about 6400 s. In the transient flow, the ion beam behavior showed rapid responses when applied voltages with or without a slew rate are assumed.