Emission Performance of Ionic Liquid Electrospray Thruster for Micropropulsion

It has been urgently required to develop ionic liquid electrospray thruster (ILET) for rapidly expanding micro-/ nanosatellites. In this work, ILETs with high-density array emitters are fabricated to quantitatively study the electrospray emission process of three typical ionic liquids (ILs). Onset voltage, current, voltage–current characteristics, and ratio of positive to negative currents are analyzed, and the effect of the properties of ILs on ILET is revealed. The onset voltage of the ILET is measured to be as low as 740 V, and the collected current is up to 100 μA. The results show that the viscosity of ILs has a great influence on the onset voltage and the emitted current. The inconsistency between theoretical and experimental results for the onset voltage of different ILs is explained in detail. Taking viscous stress into account, the estimated results agree well with the experimental ones. The analysis shows that the dynamic effect will be significant when the viscosity is high. In addition, the voltage–current characteristics and the ratio of positive to negative current are studied. The research is valuable to get insight into generative mechanism of IL electrospray and to provide a better design of both ILs and ILET.