Green Ionic Liquid Multimode Monopropellant Microthruster

A chemical microthruster was designed and tested that catalytically decomposes green ionic liquid propellant specifically designed for multimode space propulsion. The monopropellant is called FAM-110A and is synthesized by mixing [Emim][EtSO4] and HAN in the ratio of 59%-41% by weight. The microthruster is designed to produce 0.1 N thrust and fabricated from stainless steel using additive manufacturing. The catalyst is 0.3-mm-diameter Platinum-coated γ alumina. The manufactured thrusters have exit and throat areas that are up to 50% different from the design specifications due to the material type, size, and manufacturing process. The decomposition is achieved by electrically heating the thruster. Several hot fire tests were conducted and for the first time the multimode propellant FAM-110A was demonstrated in traditional catalytic decomposition thrusters. The tests were conducted for catalyst bed temperatures of 120^o C and 500^o C, and propellant flow rates of 40 µL/s and 65 µL/s. The highest temperature measured by thermocouples within the thruster interior was 650^o C.