Fabrication and propulsion performance testing of a 100 mN class resistojet thruster

This paper presents the development of a resistojet thruster utilising water and hydrogen peroxide as a propellant targeting 100 mN class thruster generation. The resistojet concept offers high specific impulse and simple design, but in small scale for micro propulsion, resistojet thrusters have been limited in their performance particularly due to insufficient propellant decomposition caused by the larger surface to volume area in downsized scale. The proposed micro resistojet thruster design features a cylindrical body with a shell and tube type heat exchanger and a resistive heating element located in the chamber. Two green propellants: water and hydrogen peroxide were used, and performance was experimentally tested. The results showed successful thermal decomposition of 50wt% hydrogen peroxide by the stainless steel heat exchanger without any catalyst employed in the chamber and also completed evaporation of water. With more enthalpy in H2O2 compared to water as propellant, higher chamber temperature, pressure, and characteristic velocity were found in H2O2 propellant case when they were tested at the same preheated initial chamber temperature condition. Both propellant cases reaching approximately 3 bar chamber pressure guaranteed supersonic flow in the micro nozzle. The clear exhaust plume from the nozzle indicated a successful thermal decomposition of hydrogen peroxide and evaporation of water.