The first micro thrust measurement of the ultrasonic electric propulsion system

Abstract

The Ultrasonic Electric Propulsion system is mainly used in space missions within the limits of 50 kg, and employs capillary standing waves as emitters to extract charged droplets in electric field. Due to multi-physics field such as ultrasonic vibration, liquid mechanics and electrostatic field in the Ultrasonic Electric Propulsion system, its thrust prediction always faces a big challenge. In this work, the thrust of Ultrasonic Electric Propulsion system is first measured by a measurement platform, and the test results are 565.23 μN, 715.65 μN and 842.73 μN with an accuracy in the order of 10% at 5 kV, 7 kV and 9 kV, and a flow rate of 5 ml/h and ultrasonic vibration frequency of 120 kHz. The test results also indicate that the thrust value increases with extraction voltage in the same flow rate with propellant and vibration frequency. Besides, the vacuum emission plume of Ultrasonic Electric Propulsion system is first investigated by a high-speed imaging technique, which reveals different emission conditions at different time such as parabolic emission trajectory and varied plume angles.