Visualizing Phase Change and Temperature Rise during Shock Loading of an Energetic Material Sample using Laser Array Raman Spectroscopy

Experimental quantification of thermo-mechanical field and chemical analysis during shock compression of a heterogeneous domain of material requires diagnostics with ultra-fast acquisition within nanoseconds. Time-gated Raman spectroscopy has been used in the past for single laser spot chemical analysis at a nanosecond time scale. Such analysis is only limited to a small domain or single measurement point on the microstructure. This work presents a novel experimental capability to perform time-gated Raman spectroscopy over multi-locations on microstructure using a laser array method. The excited Raman signal from each spot on the array was collected simultaneously on the spectrometer using a custom design of optical path. The quantification of phase change of material during the shock compression is important to model the temperature rise and to understand reaction mechanisms under shock loading of energetic materials. This technique was used to quantify the effect of friction and shock confinement at the interface between two energetic crystals. Shock-induced temperature distribution and phase-field were measured as a function of proximity between the energetic particles. The results show a strong experimentally measured correlation between temperature rise and melting of at energetic material interface as a function of microstructure variation.