Evaluation of AMU as an Ionic Liquid for Multi-Mode Propulsion Using a Porous Ionic Liquid Electrospray Thruster

Abstract

Recently, multimode propulsions that use the same ionic liquids (ILs) for electric and chemical propulsion, such as ammonium dinitramide (ADN) and hydroxylammonium nitrate (HAN), have been developed. In this study, an IL electrospray thruster was operated with an ADN-based energetic IL, and its characteristics were compared with a conventional IL, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF₄). The plume composition was analyzed using the time of flight (ToF), and the thruster performance was evaluated with an analytical balance. A broader mass distribution is observed for ADN-based energetic IL in ToF. In addition, the ADN-based energetic IL showed ranges of 225 – 415 s in specific impulse and 4.1 – 11.3% in thrust efficiency, while the conventional IL showed 446 – 876 s and 7.1 – 18.1%, respectively. Although these thruster performance obtained by the analytical balance include relatively large uncertainty due to several factors (e.g., instability in thruster operation and electrochemical reactions), the results confirm that AMU can operate as an electrospray propellant and is promising for multimode propulsion.