Dielectric characterization and microwave interferometry in HMX-based explosives

Abstract

Microwave interferometry is a useful technique for understanding the development and propagation of detonation waves. The velocity of the front can be determined directly with the dielectric constant of the explosive and the instantaneous phase difference of the reflected microwave signal from the detonation front. However, the dielectric constant of HMX-based explosives has been measured only over a small range of wavelengths. Here we employ an open-ended coaxial probe to determine the complex dielectric constant for LX-10 and other HMX-based explosives over the 5-20 GHz range. The propagation of a detonation wave in a lightly-confined cylindrical charge geometry is described where the microwave-reflective properties of the detonation front are characterized with a waveguide. For comparison, piezoelectric pins were used to measure the detonation velocity and indirectly estimate the dielectric constant of LX-10 at 26.5 GHz. Future work in this area will also be discussed. © Published under licence by IOP Publishing Ltd.