Electromagnetically induced localized ignition in secondary high explosives: Experiments and numerical verification

Perry, W. Lee; Gunderson, Jake Alfred; Glover, Brian; Dattelbaum, Dana M.

doi:10.1063/1.3606409

Cited by 17 publications

(17 citation statements)

References 12 publications

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“…We used our MWIR microscope to detect hot spots created in two ways, using either THz radiation from a long-wavelength IR (LWIR) laser or an ultrasonic horn. These methods do not create hot spots by inputting energy into a tiny spot, 4 or by spiking the EM with tiny absorbing inclusions, 5 but instead they input energy in a spatially diffuse, homogeneous manner, which allowed the hot spots to develop spontaneously in microstructured sample materials.…”

Section: Introductionmentioning

confidence: 99%

Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy

Chen

You

Suslick

et al. 2014

Review of Scientific Instruments

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We have observed and characterized hot spot formation and hot-spot ignition of energetic materials (EM), where hot spots were created by ultrasonic or long-wavelength infrared (LWIR) exposure, and were detected by high-speed thermal microscopy. The microscope had 15-20 μm spatial resolution and 8.3 ms temporal resolution. LWIR was generated by a CO2 laser (tunable near 10.6 μm or 28.3 THz) and ultrasound by a 20 kHz acoustic horn. Both methods of energy input created spatially homogeneous energy fields, allowing hot spots to develop spontaneously due to the microstructure of the sample materials. We observed formation of hot spots which grew and caused the EM to ignite. The EM studied here consisted of composite solids with 1,3,5-trinitroperhydro-1,3,5-triazine crystals and polymer binders. EM simulants based on sucrose crystals in binders were also examined. The mechanisms of hot spot generation were different with LWIR and ultrasound. With LWIR, hot spots were most efficiently generated within the EM crystals at LWIR wavelengths having longer absorption depths of ∼25 μm, suggesting that hot spot generation mechanisms involved localized absorbing defects within the crystals, LWIR focusing in the crystals or LWIR interference in the crystals. With ultrasound, hot spots were primarily generated in regions of the polymer binder immediately adjacent to crystal surfaces, rather than inside the EM crystals.

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Section: Introductionmentioning

confidence: 99%

Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy

Chen

You

Suslick

et al. 2014

Review of Scientific Instruments

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“…To further illustrate the how the quantity of EM "active" gas phase species develops after laser surface heating over time, a COMSOL model was run. The COMSOL multiphysics modeling platform incorporates the established kinetic model of HMX referred to above [17]; the details of the 4-step reversible kinetics and associated rate equations for HMX, and how they are used in COMSOL modeling, have been covered in previous publications [2,21]. In this case, the model was built for 1D surface heating, the laser pulse was applied for 13 ms, and the reaction continues to grow up to 16 ms, then dies out.…”

Section: Resultsmentioning

confidence: 99%

“…fire). While spark initiation is technically electromagnetic (EM) in nature, the general effect of EM energy on initiation has only been sparsely investigated [1][2][3][4][5][6]. The motivation for understanding this effect comes from our increasing dependence on radar and wireless communication sources in environments where explosives and weapons are present.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic enhanced ignition

Duque

Perry

2017

Combustion and Flame

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Here, we investigate how EM radiation affects the thermal decomposition pathway in HMX. The experiment used an external heat source (CO 2 laser) to rapidly heat the surface of HMX and observe the response upon application of EM energy that, on its own, is not enough power to induce heating or ignition. We hypothesize that charged intermediate decomposition species and free radicals in the gas phase interact strongly with EM energy, leading to plasma formation. These gas phase species form as a result of HMX sublimation and decomposition, and will act as "virtual antennas" and strongly couple to EM energy. The rapid absorption of EM energy during this coupling event is observed in the measured reflected power data. Ignition and plasma formation were monitored using both visible and IR photodiode probes, as well as imaged using a high-speed video camera. These observations support the hypothesis that the presence of an EM field will perturb the thermal decomposition pathway of HMX, and cause ignition to occur at a lower temperature than what is predicted under typical thermal conditions. This intense interaction results in electrically excited molecules that propagate the energy and surpass the activation barrier for ignition before the predicted ignition temperature of the bulk sample has been reached. Understanding the decomposition of energetic materials under the influence of EM energy is important to understand and predict material response under a variety of environmental conditions.

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“…Consequently, recent approaches to enhance heating have focused on the intentional inclusion of absorptive particles such as SiC and carbon nanotubes [14][15][16][17]. The focus of these studies, however, has been primarily to study localized hot spot formation and ignition within these materials rather than to develop a fundamental understanding of the response of neat explosives to electromagnetic energy.…”

Section: Introductionmentioning

confidence: 99%

X‐Band Microwave Properties and Ignition Predictions of Neat Explosives

Daily

Glover

Son

et al. 2013

Propellants Explo Pyrotec

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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.

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Electromagnetically induced localized ignition in secondary high explosives: Experiments and numerical verification

Cited by 17 publications

References 12 publications

Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy

Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy

Electromagnetic enhanced ignition

X‐Band Microwave Properties and Ignition Predictions of Neat Explosives

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