Micro to mesoscale temperature gradients in microwave heated energetic materials

摘要

Temperature gradients will appear in any microwave-heated heterogeneous system where there is contrast in the complex permittivity of the constituent materials. The magnitude of the gradients depends on several factors that include the permittivity, thermal conductivity, length scale, and thermal diffusivity. In general, it is challenging to measure the absolute temperature accurately in a strong microwave field; the presence of large gradients can further complicate the interpretation of temperature measurements. These issues are especially important during the microwave heating of highly exothermic chemical reaction systems, such as those containing explosives or propellants. It was therefore the intent of this work to theoretically and numerically investigate the nature of microwave-induced thermal gradients in energetic systems over a wide range of length scales, primarily for the purpose of interpreting temperature measurement.