Two-Dimensional Microfabricated Colloid Thruster Arrays

Abstract

This paper reports the preliminary development and experimental characterization of a planar array of micro–fabricated electrospray emitters, intended for space propulsion applications in micro–satellites. Electrospray engines take advantage of the electrohydrodynamic effect known as Taylor cone to produce thrust. The array is designed with an open architecture and is composed of a set of spikes, i.e., emitters, coming out from a propellant pool. The emitters were fabricated in two configurations: fully sharpened emitters, i.e., pencils, and truncated emitters, i.e., volcanoes. The engine has anywhere from 4 up to 1025 emitters in a 0.64 cm active area. The engine hydraulics is covered with black silicon that acts as wicking material. This paper briefly discusses the micro-fabrication of the engine and provides experimental characterization of the hydraulics system including wettability tests, current-versus-extraction voltage data, and the imprints of the exit stream on collectors. A preliminary demonstration of the possibility of using temperature control to obtain substantially larger emission currents for the same extraction voltage is also provided. The paper preliminarily compares the results the theory of field emission for electrons, to finally point out the tentative future work.