Microwave and Electrochemical Stimulation for Control of Ignition and Throttling of Energetic Materials

While thermal and mechanical means are the most common approach to stimulate energetic components, alternative methods are also available. Laser ignition in both the visible and IR have also been used. In this talk I will discuss using microwaves (MW) and electrochemical means (EC) to stimulate, and modulate the energy release process. Unlike surface stimulation of the bulk materials, microwave heating offers the potential to trigger energy release within the energetic spatially and temporally, thus enabling the in-operando spatially selective control of the throttling. We give examples of employing reactive microwave sensitizers, Ti and MnO2 to trigger the localized ignition of non-microwave sensitive energetic components. In addition we demonstrate that by embedding wires which can act as a microwave receiving antennas we can both initiate ignition locally, or alternatively accelerate the burn rate locally.<br/>In a second approach we demonstrate a new concept through which the volatility of a high energy density liquid propellant can be dynamically manipulated enabling one to (a) store a thermally insensitive oxidation resistant non-flammable fuel (b) generate flammable vapor phase species electrochemically by applying a direct-current voltage bias and (c) extinguishing its flame by removing the voltage bias, which stops its volatilization. We show that a thermally stable imidazolium-based energy dense fuel, can be made flammable or non-flammable by application or withdrawal of a direct-current bias. This cycle can be repeated as often as desired. The estimated energy penalty of the electrochemical activation process is only ~ 4% of the total energy release.