Study on the control of propellant flow by electric field in ionic liquid electrospray thruster

Ionic liquid electrospray thruster is one of the best candidates for micro satellite because of its high thrust accuracy, high specific impulse and low power consumption. The flow rate of this type of thruster is in the order of nL/s. The propellant can be actively supplied through the valve which is usually complex, or passively supplied by capillary force, which is at the risk of thruster failure caused by propellant overflow. Therefore, a compact and accurate flow control structure is needed. Based on the principle of electrocapillary, a design concept of reversible electric valve which can control the state of “on-off” and the flow rate of propellant by electric field is presented in this study. The simulation and experimental results show that this electric valve can fast and reversibly control the “on-off” state of propellant, the flow rate is unstable and there is an upper limit due to the gravity and the contact angle saturation, while it can reach 0.229 nL/s stably when the AC voltage is 480 V under non-gravity condition. This electric valve is compact, reversible, fast and high precision, which is expected to be applied to ionic liquid electrospray thrusters to achieve high precision flow control and thrust regulation.