Slit Colloid Thrusters Using Ionic Liquid Propellants

Busek proposes to develop and demonstrate a milliNewton slit colloid thruster (SCT) system and at the conclusion of the program deliver the thruster prototype to the government. During Phase I, Busek confirmed the feasibility of the SCT and established the preferred slit geometry that is suitable for large scale arraying. It was shown that a slit emits from a series of closely spaced individual Taylor cones forming a sheet of colloids. The time-of-flight spectra associated with this sheet electrospray indicate high propulsive efficiency regimes of particular interest to this project. In the Phase II program we propose to further develop the basic thruster array element and characterize it using unique methods for achieving uniform propellant distribution, stable emission, and direct thrust measurement. The development will be supported by modeling efforts by MIT and ionic liquid propellant optimization studies by Yale University. An array of multiple SCT elements will then be developed, allowing for convenient and precise scaling to the milliNewton range, while maintaining propulsive efficiencies of 70% and specific impulse up to 1000s. This expected performance is unmatched by any other electric propulsion device operating in the milliNewton thrust range, including the main competitor, liquid metal based FEEPs.