Combustion Characteristics of a Hydroxylammonium-Nitrate- Based Monopropellant Thruster with Discharge Plasma System

摘要

Hydroxylammonium-nitrate-based monopropellant thrusters have been continuously researched as a replacementfor conventional hydrazine thrusters. An ignition system using the discharge plasma of noble gas, called a dischargeplasma system, has been proposed in substitution for the conventional solid catalysts. However, the combustioncharacteristics of the thruster are not well understood. The present study conducted firing tests of a 1-N-class thrusterwith the discharge plasma system under a vacuum condition. The objectives of the study were to experimentallyevaluate the effects on the combustion characteristics of the combustion chamber characteristic length and thepropellant injection method by the measurement of thrust and pressure. In this paper, the combustion characteristicsof the monopropellant are discussed by considering the characteristic exhaust velocity efficiency and powerconsumption. In addition, the thruster lifetime is evaluated in terms of electrode degradation. With the non-atomizedinjector, a maximum thrust of 0.34 N is achieved at an argon mass flow rate of 0.15 g /s, a hydroxylammoniumnitrate-basedmonopropellant mass flow rate of 0.34 g /s, and a combustion chamber characteristic length of 508 mm.In addition, it was observed that a shorter combustion chamber characteristic length increased the characteristicexhaust efficiency. At an accumulated firing time of 1646 s, no effect of electrode degradation on the performance ofthe thruster was observed.