Shock Compression Induced Hot Spots In Energetic Material Detected By Thermal Imaging Microscopy

The chemical reaction of powder energetic material is of great interest in energy and pyrotechnic applications since the high reaction temperature. Under the shock compression, the chemical reaction appears in the sub-microsecond to microsecond time scale, and releases a large amount of energy. Experimental and theoretical research progresses have been made in the past decade, in order to characterize the process under the shock compression. However, the knowledge of energy release and temperature change of this procedure is still limited, due to the difficulties of detecting technologies. We have constructed a thermal imaging microscopy apparatus, and studied the temperature change in energetic materials under the long-wavelength infrared (LWIR) and ultrasound exposure.\footnote{M.-W. Chen, S. You, K. S. Suslick, and D. D. Dlott, {\textit{Rev. Sci. Instr.}, \underline{\textbf{85}}, 023705 (2014)},}\footnote{ M.-W. Chen, S. You, K. S. Suslick, and D. D. Dlott, {\textit{Appl. Phys. Lett.}, \underline{\textbf{104}}, 061907 (2014)}} Additionally, the real-time detection of the localized heating and energy concentration in composite material is capable with our thermal imaging microscopy apparatus. Recently, this apparatus is combined with our laser driven flyer plate system\footnote{K. E. Brown, W. L. Shaw, X. Zheng, and D. D. Dlott, {\textit{Rev. Sci. Instr.}, \underline{\textbf{83}}, 103901 (2012)}} to provide a lab-scale source of shock compression to energetic material. A fast temperature increase of thermite particulars induced by the shock compression is directly observed by thermal imaging with 15-20 $\mu$m spatial resolution. Temperature change during the shock loading is evaluated to be at the order of 10$^9$K$/$s, through the direct measurement of mid-wavelength infrared (MWIR) emission intensity change. We observe preliminary results to confirm the hot spots appear with shock compression on energetic crystals, and will discuss the data and analysis in further detail