Thrust Augmentation of Solid Rocket Motors Using Beamed Microwave Energy

A method fir augmenting the thrust of a solid rocket motor by coupling beamed microwave energy to alumina particles in the diverging section of a nozzle is analyzed. Coupling of microwave radiation with micron-sized alumina particles increases the particle temperature. The main mechanism of thrust increase is expected to be gas particle collisions that transfer the increased energy of particles to kinetic energy of the expanding gas. A dynamic power-generation and beaming scheme has been designed to produce 1.0 GW of power at a launch vehicle throughout the first 50 km of its ascent trajectory. Microwave coupling to alumina particles has been investigated experimentally. A two-phase, two-way coupled numerical model has also been developed to assess the increase in propulsive performance. The developed numerical capability has been used to calculate nozzle flowfields for two different solid rocket motors with and without the addition of beamed microwave radiation. High gas density and fast collisional relaxation result in the efficient transfer of microwave energy to the kinetic energy of the flow. The total thrust in both cases was found to increase by approximately 0.5% for a 100 MV/m(2) microwave beam and by 6% for a 1 GW/m(2) beam.