Rapid startup of hydroxyethylhydrazinium nitrate ionic monopropellant thruster using rotating arc plasma jet

Abstract

In this study, a thruster was developed by integrating a plasma reactor upstream of a catalyst bed and utilizing a plasma-arc jet to preheat the catalyst bed within 30 s. A plasma-assisted monopropellant thruster was designed for high-performance ionic monopropellants that require catalyst preheating. Hydroxyethylhydrazinium nitrate was selected as the monopropellant because of its easy synthesis and low adiabatic combustion temperature, which allow the use of conventional materials. Nitrogen or air (10 SLPM) was used as the plasma discharge gas, with a 20 kHz AC power supply generating plasma by passing 0.7 A current through the discharge gas. The Ru/LaAl₂O₃ catalyst bed was preheated using a plasma-arc jet with both nitrogen and air, reaching 763 K within 30 s. Subsequently, the propellant tank was pressurized to 0.4 MPa and 0.7 MPa to verify propellant decomposition under low and high mass flow rate conditions. The results confirmed the propellant decomposition under both nitrogen and air discharge conditions. This study demonstrates that the developed plasma-assisted monopropellant thruster offers a novel method for operating thrusters with high mass flow rates (> 1 g/s) during emergencies.