Abstracted Random Mediums for Electromagnetic Hotspot Observation in Finite-Difference Time-Domain Simulation

Microwave excitation of energetic materials can remotely incite ignition and deflagration. While this has been experimentally observed, the underlying principles are not well understood due to the complexity of analytical solutions. Further complicating understanding is the sensitivity of the effect to geometry and the difficulty of creating simulation environments representative of realistic materials. Manageable analysis requires abstractions, and here abstractions ranging from regularly arranged spheres and cubes to randomly arranged spheres, cubes, and arbitrarily shaped crystals are examined. The randomly arranged cube model provides acceptable prediction of thermal and peak electric field hotspots while having manageable computational complexity. The hotspots resulting from multiple subwavelength scattering occur inside the body of the energetic material and are localized in time and space having spans that are a few percent or less of the period and wavelength of pulsed electromagnetic excitation.