Prototype Cryogenic Solid Hydrogen Storage and Pellet Injection System for Combustion

Liquid hydrogen is currently the fuel of choice for large-thrust propulsion systems because its high specific impulse more than compensates for its low density. Although more energetic fuels have been shown to exist through projects such as the Air Force High Energy Density Materials Program, these fuels are unstable enough to not yet be practical. It has been proposed to add these energetic materials to cryogenic solid molecular hydrogen to form a stable, superior-performance fuel. Solid cryogenic propellants may even emerge as an important part of what the American Space Exploration Initiative has recently recognized as the critical national technology of cryogenics. Based on the technology of pellet fueling of fusion plasmas, this proposal first describes the design of a prototype solid hydrogen propellant system for combustion studies. The hydrogen is condensed directly into a solid, extruded, formed into pellets, and injected into a combustion chamber. The primary remaining feasibility issues of such a system: pellet interaction with combustion, rapid solid condensation from a gas, and the development of a high feed rate injector, will also be addressed. The proposed work is expected to provide basis for a practical solid hydrogen rocket propulsion system.