Numerical investigation on plume characteristics and propulsive performance of ionic liquid electrospray thruster based on mixed ion model

Abstract The ionic liquid electrospray thruster (ILET) is highly promising for micro/nanosatellite propulsion and receives widespread attention. In order to further improve the performance of ILETs, based on the particle-in-cell method, this study numerically investigates the effects of plume ion composition on plume characteristics, including ion distribution and electric field distribution, as well as propulsive performance of ILETs, operating in both uni-thruster and bi-thruster modes. A more realistic mixed ion model is utilized, incorporating dimer and trimer ions in the plume in addition to the commonly considered monomer ions. The results show that the presence of dimer ions significantly alters the ion distribution of plume and affects the thrust and specific impulse of ILET in both modes. In the uni-thruster mode, the plume evolves from a uniform semicircular shape to a more complex structure, with polymer ions aggregated in the central region and monomer ions dispersed in the external region, as the proportion of dimer ions increases. Due to the phenomenon of ion reflux, thrust and specific impulse also increase with the dimer ion ratio. In the bi-thruster mode, the ion distribution of plume becomes more concentrated in the external region with the addition of dimer ions, and the optimal performance is achieved with a dimer ion content of 30%. These findings provide valuable insights into the behavior of ion thrusters and offer guidance for optimizing the performance of ILET in practical space applications.