Feasibility and Potential Applications of the Microwave Electrothermal Thruster for Orbital Transfer Vehicles

This work examines the potential of the Microwave Electrothermal Thruster (MET) as a propulsion option for Orbital Transfer Vehicles (OTVs). The MET uses microwave energy to heat a gaseous propellant without electrodes, allowing higher operating temperatures and specific impulse than typical electrothermal devices. A 1-kW water-fueled MET is modeled and compared with representative chemical and electric thrusters, accounting for system considerations under realistic OTV constraints. The results indicate that the MET offers intermediate performance between chemical and electric thrusters, making it suitable for missions with high total impulse requirements and constraints on admissible transfer time. A sensitivity study is performed, showing that power processing unit efficiency plays a critical role and that current values would greatly limit the useful operating range, thus identifying this as a major future development area.