Measuring the loss of crystallinity during a detonation with visible light scattering

• Main Authors: Bowlan, Pamela, Smilowitz, Laura, Henson, Bryan, Remelius, Dennis, Suvorova, Natalya, Oschwald, Dave
• Format: Conference Proceeding
• Language: English
• Subjects: Absorptivity; Chemical reactions; Chemistry; Crystal structure; Crystallinity; Detonation waves; Diagnostic systems; Explosives; Light scattering; Morphology; Pressurization; Reaction kinetics; Solid phases
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/12.0001095

A detonation wave is a supersonic wave of chemistry, which in solid explosives, propagates across a material converting the initial bed of crystals into a high pressure fluid of product species within nanoseconds. A subsequent rapid expansion of the fluid is how explosives do work. While secondary solid explosives are widely used it is still often not possible to predict if or when an impulse (heating or pressurization) will lead to a detonation wave which is a serious problem for the safety and performance of an explosive. One reason for this uncertainty is that little is known about chemical kinetics in a solid, where the rate limiting step is likely the solid coming apart. To better understand the role of crystallinity in detonation chemistry, here we describe an in situ, ultrafast diagnostic of crystalline morphology using light scattering from a femtosecond laser. Our initial findings suggest that the detonation wave begins in the solid phase, and that the detonation chemistry converts the scattering solid into a non-scattering absorptive fluid. The time scale of the light scattering matches with chemical reaction durations reported in the literature, suggesting that this is tracking the chemical kinetics which govern detonation.