Simulating Plasma Ignition of HMX via Microwave Radiation at Substandard Bulk Temperatures

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is an energetic material used in a range of applications from plastic bonded explosives (PBX 9501, LX-14, etc.), solid rocket propellants, to military applications. Over the past decade, HMX (neat, doped and PBX) has been studied in microwave fields (MWFs). Although the direct interaction of neat HMX with MWFs is minor, it is hypothesized that the gas-phase intermediates generated by thermal decay strongly couple to the MWFs resulting in ignition at substandard bulk temperatures. In this work, simulations will provide insight to experiments that observed the plasma ignition of gaseous intermediates. We couple the Fridman-Macheret α-Model (plasma), reversible chemical kinetics, MWF and heat transfer within COMSOL Multiphysics software suite. These simulations will provide support for our hypothesis that the intense optical signal observed during the microwave pulse is the result of the ignition of HMX intermediates that couple to the MWFs.