Integrated Green Monopropellant Propellant Processing for High Power Electrospray Thrusters

Green monopropellants have numerous performance and handling benefits over conventional propellants such as hydrazine. Many are derived from Ionic Liquids (IL) and are therefore well suited for use in electrospray electric propulsion systems. This affords the possibility of a multi-mode propulsion (MMP) capability, where both chemical and electric thrusters share a common propellant. Recently, Busek became the first to operate an electrospray thruster in space via the NASA ST7/ESA Pathfinder mission. Busek is also a leader in developing novel green monopropellant thrusters and is therefore poised to create and demonstrate MMP systems. Busek proposes to address presently gating challenges associated with electrospray-MMP systems. First, high thrust density emitters will be developed within the strict material compatibility constraints imposed by candidate propellants. Subsequently, an inline propellant processing unit will be developed to both appropriately distribute the liquid phase propellant and provide electrical isolation. In Phase I, the thruster head performance will be optimized towards high T/P and Isp >1000s, through targeting efficient nanodroplet beams, and demonstrated with propellant supplied via the inline processing unit. In Phase II the technology will be scaled towards a high power, 100s of W, system operated end-to-end with Buseks existing green monopropellant compatible tanks and valves.