X‐Band Microwave Properties and Ignition Predictions of Neat Explosives

Abstract

Microwave frequency electromagnetic properties are critical for understanding and predicting the heating and ignition behavior of explosives subjected to microwave irradiation. In this work we report relative complex permittivity measurements in the X‐band (8–12 GHz) for 13 neat explosives measured by the circular cavity technique. This data set was then used in conjunction with COMSOL 4.3 Multiphysics® finite element analysis software to design and simulate a low power (100 W), high electric field X‐band microwave applicator. The role of the sample holder on our ability to directly study the response of explosives to electromagnetic energy is examined and shown to be critical. Times to ignition were predicted for PETN, TATB, and HMX and indicate that for the proposed applicator and considered properties ignition may occur in less than one second exposure. These predictions show that explosives can be effectively heated in short time scales through direct microwave heating without absorptive binders or inclusions.

Using Neutron Diffraction to Investigate Texture Evolution During Consolidation of Deuterated Triaminotrinitrobenzene (d-TATB) Explosive Powder

“…Accordingly, the ideal as-pressed length of the pellet is 22.9 mm. Typical densities for neat-pressed TATB range from 1.8 to 1.9 g/cc [6,31,32]. For a 9.5-mm diameter pellet at a 1:1 aspect ratio (i.e., height of 9.5 mm), a pressure of 41.4 MPa is usually sufficient to press normal TATB to 1.80 g/cc [33].…”

Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena

“…Losses in TNT have been reported in Ref. [11] at microwave frequencies (10 GHz). The losses reported here are ten times larger, but the operating frequency is much higher (94 GHz).…”

“…Cawsey et al [10] studied high explosives at 34.5 GHz for various densities by applying the resonant cavity method. Daily et al [11] derived the dielectric constant of thirteen reactive materials in the 8-12 GHz frequency range with the circular cavity technique. Higginbotham Duque et al [12] developed a cavity perturbation method to analyze nine materials based on TATB, RDX and HMX from 1 to 18 GHz.…”

Microwave-assisted modulation of light emission intensity in alkali-pyrotechnic plumes

“…Microwave energy transfer to condensed phase reactants of energetic materials containing electrically conductive phases (e.g., metal fuels) is expected to be higher due to eddy current heating [16] , which, for metal spheres, is a function of the particle size and microwave penetration depth [17 , 18] . In order to improve microwave absorption of most non-metallized energetic materials [19][20][21] , additives with high dielectric loss have been included [22 , 23] .…”