2018.B.2.3. The Design and Characterization of a Porous-emitter Electrospray Thruster (PET-100) for Interplanetary CubeSats

Author(s)

Chengyu Ma (1)
Charlie Ryan (1)

University of Southampton, United Kingdom

Session

B.2

Keywords

electrospray thruster, micro-propulsion, CubeSat, interplanetary

Abstract

Using nanosatellites for interplanetary flights is an advanced mission concept in space industries, but the development of an effective on-board micro-propulsion system for such mission has been a main challenge due to the constraints in terms of size, mass and power capability of a nanosatellite. Among various micro-propulsion concepts, electrospray thrusters is a promising candidate due to the high specific impulse, which can be higher than 4000 s, and the compact system configuration. An electrospray thruster utilizes a strong electric field to extract and accelerate charged particles from the surface of a liquid propellant, which is generally an ionic liquid, held on the tip of a protruding emitter. The emitters are generally multiplexed to increase the over thrust output because the thrust of a single emission site is only at the level of 0.1 µN. This paper introduces the development of an electrospray thruster with a porous glass emitter, which has an array of 100 emitter tips, manufactured through computer-numerical-controlled machining. A porous reservoir was used to passively transport the propellant to emitter tips using capillary action, leading to a pressure-free thruster configuration. The overall size of the thruster is 4 cm × 4 cm × 3 cm. The thruster was tested in a vacuum chamber at the University of Southampton, and its propulsive performance was characterized using a time-of-flight (ToF) system, showing a specific impulse higher than 7500 s, a thrust higher than 220 µN with a total thruster power around 14 W and a power efficiency of 62%. With this specific impulse, a propellant mass of only 12.7% of total satellite mass is required for 10 km/s velocity change. Several issues regarding the electrochemical effects and the plume angle should be further studied and improved.