2018 Volume 16 Issue 2 Pages 177-180
This paper describes the performance of a proposed bipropellant thruster using nitrous oxide (N2O) and dimethyl ether (DME). Conventionally, nitrogen tetroxide and hydrazine are used in thrusters for spacecraft, but requires gas treatment systems in the ground tests due to toxicity and reactivity to materials. Hence, we proposed to apply N2O and DME to a bipropellant thruster in order to develop a compact and eco-friendly bipropellant thruster. N2O and DME, which are liquefied gas, are neither toxic nor reactive to materials, and require no gas treatment system in the ground tests. Furthermore, the combustion chamber can be downsized because gaseous injection can eliminate the evaporation time. The application vapor pressures of 6.4 MPa (N2O) and 0.6 MPa (DME) at 25 °C to self-pressurization would eliminate the necessity of pressurant to simplifies the feeding systems. In this study, a 0.4-N class N2O/DME bipropellant thruster with two types of injector was prototyped, and tested in a vacuum chamber to clarify the dependence of injector design on characteristic velocity (C*) efficiency. Using an injector consisting of showerhead and subsequent 15-mm orifice, the thruster yields combustion chamber pressure of 0.27 MPa, with corresponding C*efficiency of 68.3 % at O/F = 3.5.