Ignition of the Droplets of Ammonium Dinitramide-Based High-Energy Ionic Liquid

Abstract

Mixtures of ammonium dinitramide (ADN), monomethylamine nitrate (MMAN), and urea form stable ADN-based energetic ionic liquids (EILs), even below room temperature. These mixtures, referred to as EIL propellants, can be highly energetic and yet are easy to handle. This study focuses on the ignition of ADN-based EILs in a thermal apparatus. We consequently ignited ADN-based EIL droplets within 590 ms using 2 W of the continuous-wave laser. The results suggest that laser ignition is a feasible new ignition system for thrusters. The condensed-phase reaction of the ADN-based EILs started immediately after heating, and gases evolved from the reaction ignited when the droplet temperature reached approximately 400°C. Thermal analyses indicated that the amount of heat generated by the condensed-phase reaction of the EILs affected their ignitability. The analysis of the evolved gases indicated that methyl nitrate gas generated from the condensed-phase reaction of MMAN ignited first, followed by the ignition of other gases because of heat from the flame of the methyl nitrate. These results clarify the ignition requirement of ADN-based EILs and should be useful in the design of new EIL compositions.