Electrospray of HAN-based Monopropellant

Multimode in-space propulsion is the integration of two or more propulsive modes with shared propellant into a single spacecraft propulsion system. Multimode chemical-electric propulsion is particularly attractive because of its potential to enhance mission flexibility, enable new missions, and provide spacecraft mass savings. However, a major challenge is propellant compatibility between the chemical and electric modes. The advent of ‘green’ HAN-based energetic ionic liquid monopropellants offers a promising solution that may enable combination of monopropellant chemical and electric electrospray propulsion. This presentation focuses on the current state-of-the-art in electrospray of HAN-based monopropellants and highlights key challenges and unexplained behavior unique to these liquids. The presentation incorporates recent insights from literature across the broader community as well as the presenter’s own on-going research with a customized and tailored HAN-based monopropellant. In particular, this presentation highlights the importance of water content, double-salt behavior, proton exchange reactions, and plume surface interactions on the future engineering and physics-based understanding of electrospray of HAN-based monopropellants.