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Future mission requirements of energetic material systems demand the ability to a tune the output (burning rate, thrust, specific impulse, radiant emission) of a broad range of energetic materials. More specifically for solid propellants, considerable work has been conducted on the development of electrical and valved throttling techniques. However, these techniques are either formulation-specific or are propellant temperature limited. Conversely, the proposed plasma throttling technique has been demonstrated with a number of solid propellant and pyrotechnic compositions and is not formulation specific. This enables throttling of higher performance energetic systems. In this method, a pulsed microwave source is used to deposit energy to the gas-phase flame of a burning energetic material. Steady combustion of the energetic material is perturbed to an unsteady state through microwave absorption within the gas-phase flame of an energetic material that is doped with materials which themselves or in decomposition produce species which readily couple with microwave irradiation within the gas phase combustion flame in order to produce ionization and/or formation of a plasma. The resulting enhanced energy feedback to the burning surface enables drastic enhancement of energetic material burning rate.

• Enhanced control: Throttling of the combustion rate of an energetic material

• Enhanced performance: Resulting plasma and flame temperature increase enhances radiometric emission of pyrotechnics (e.g. decoy flares) and may also enhance specific impulse of propellants.

• Formulation-independent throttling of the combustion of energetic materials, enabling throttling the performance of a broad range of energetics (composite, double-base, CMDB propellants, and pyrotechnics)

• Unobtrusive, light weight technique: No heavy or flame-exposed hardware is required; throttling hardware exists outside the region of combustion

• High tunability: Pulsed microwave deposition can allow high tunability of propellant combustion through control of repetition rate and duty cycle

Solid/hybrid/liquid propulsion, pyrotechnics

J. Lynch, M. Ballestero, R. Cazin, J. B. Michael, T. R. Sippel, “Microwave-Supported Plasma Combustion Enhancement of Composite Solid Propellants Using Alkali Metal Dopants,” to be presented at the 54th AIAA Aerospace Sciences Meeting, Jan. 4-8, 2016, San Diego CA.