The MET (microwave electro-thermal) thruster using water vapor propellant

Summary form only given, as follows. The Research to develop the MET (Microwave Electro-Thermal)Thruster at Research Support Instruments and University of Pennsylvania using a variety of gases as fuel is described. The Microwave thermal thruster has undergone dramatic evolution since its first inception and is now entering flight development. The MET uses an electrodeless, vortex stabilized microwave discharge to superheat gas for propulsion and in its simplest design, uses a directly driven resonant cavity empty of anything except gaseous propellant and the microwave fields that heat it. It is robust, simple inexpensive thruster with high efficiency and has been scaled successfully to operate at IOOW, IkW, and 50kW using 7.5, 2.45 and 0.9I5Ghz microwaves respectively. The 50KW at 0.915GHz continuous operation being perhaps the highest power demonstration of any steady state Electric thruster. The MET can use a variety of gases for fuel but the use of water vapor has been shown to give superior performance, with a measured I,, of greater than 800 sec. When this added to the safety, ease of storage, and transfer of water in space, the potential exists for using water fueled MET as core propulsion system for many re-fuel capable space platforms.