Student: Adam Lawrence, Graduate Student in Mechanical Engineering, Iowa State University
Faculty Advisor: Dr. Travis Sippel
Microwave Enhancement and Control of Boron-based Solid Propellants
Increasing the performance and control of propulsion systems will help enable the next generation of NASA missions. Solid propellants are often used for reliable, energy-dense, high-performance propulsion. However, they still suffer from inefficiencies due to incomplete combustion and cannot be throttled like liquid propellant systems. Metal fuel particles, such as aluminum or boron, are often added to increase performance but these particles require high, sustained temperatures for complete combustion. This can create inefficiencies and limit the capabilities of solid propellants, and this is especially prevalent in boron-based propellants. My research focuses on enhancing the performance and control of solid propellants by applying microwave energy. Microwave energy frequencies are absorbed very well by certain combustion products produced by metalized solid propellants. This added energy can significantly increase combustion temperatures and the burning rate of the propellant, which indicates higher thrust values. This technique offers not only a performance increase of current solid propellant formulations but also enables the control of solid propellants to thrust output using electromagnetic energy traveling at the speed of light. Microwave enhancement of solid propellants would enable ignition, enhancement, and throttling of metalized, solid propellants without requiring the integration of large, heavy mechanical throttling systems. This method would use the motor casing as a waveguide and only require the addition of a power source and magnetron, making it ideal for volume and mass-limited applications such as ramjet or scramjet systems. This technology could enable the next generation of aerospace systems, including supersonic and hypersonic vehicles.