Study on the emitter infiltration of needle-capillary ionic liquid electrospray thruster

This article proposes a new emitter structure of needle-capillary ionic liquid electrospray thruster and carries out numerical simulation and theoretical analysis to discover the emitter infiltration effect under the conditions of no liquid supply and liquid supply. Emitter physical dimensions L, d, θ, β and the contact angles α, γ between the ionic fluid and the structure jointly determine the configuration of the meniscus. By analyzing the influence of various variables on the infiltration, a complete emitter infiltration law of needle-capillary ionic liquid electrospray thruster is summarized. In addition, the phenomena of infiltration relaxation and periodical infiltration oscillation are found in the numerical simulation under the condition of liquid supply, which provide an important basis for the optimization of the emitter structure. Considering Bond number ≪ 10−2 and working in a space environment, the liquid is mainly affected by surface tension and viscous force. Meanwhile, the meniscus formed by the ionic fluid satisfies the requirement that it has rotational axis symmetry and constant mean curvature surface, thereby obtaining the mathematical analytical expression of the quasi-static meniscus, the Delaunay surface. The numerical simulation results and analytical solutions are fitted, and an excellent consistency is obtained with an extremely small fitting deviation. Besides, the classification inferences of the type of Delaunay surface to which the meniscus belongs to are explored.