Laser-induced air shock from energetic materials (LASEM): a novel microscale technique for characterizing energy release at high heating rates

In this review we detail the expansion of laser-induced shock waves into the air following nanosecond-pulsed laser ablation of energetic materials for comparison of the microsecond-timescale energy release among different samples; subsequent self-sustained combustion reactions provide information about the millisecond-timescale energy release. This technique is called laser-induced air shock from energetic materials (LASEM). A detailed description of the processes involved in LASEM is presented, along with the experimental conditions for successfully differentiating similar energetic materials. The influence of material properties and sample preparation, laser properties, high-speed imaging parameters, and data fitting methodology on the characteristic laser-induced shock velocities is reviewed with relevant examples. Related work by other groups is also discussed, demonstrating the increasing usage of laser-induced plasmas and their subsequent effects for energetic material characterization on a laboratory scale. We provide examples of recent capability upgrades. Finally, we enumerate the open questions relating to LASEM experimental results and their relationship to detonation chemistry.