Ultra‐High Fidelity Laser‐Induced Air Shock from Energetic Materials

Abstract

Recent interest in the implementation of the Laser‐induced Air Shock from Energetic Materials (LASEM) technique prompted an investigation using ultra‐high‐speed imaging diagnostics to provide early‐time (sub‐μs) shock‐wave‐radius‐versus‐time data necessary to accurately determine the characteristic laser‐induced‐shock velocity (y‐intercept) for high explosives (HE) of interest. Ultra‐high‐speed focused‐shadowgraphy images were collected from nanosecond‐pulsed laser‐ablated samples of HE similar to those in the published literature. Shadowgraphy images were collected using interframe times ranging from 50–750 ns, with exposure times of 5 ns. Acquired shock‐wave‐radius‐versus‐time data permitted a high‐fidelity assessment of the shock wave velocity produced at the characteristic radius of the generated laser‐plasma pulse. The resulting data from eight different HE indicated that early‐time energy contributions and the resulting laser‐induced shock velocity profiles produced from ablation of the HE material were indistinguishable amongst the explosives tested for the majority of the time domain characterized (0–12 μs).

Fast explosive performance prediction via small-dose energetic materials based on time-resolved imaging combined with machine learning

“…By means of plume morphology assessment, aerodynamic analysis, spectra detection, and vibrational temperature calculation, it was concluded that the exothermic chemical reactions occurring at around 25 μs in plasma were closely correlated to the macroscopic detonation processes, which is consistent with published results stating that the exothermic chemical reactions occur between 12 to 100 μs after pulsed lasers loading. 13,31…”

“…By means of plume morphology assessment, aerodynamic analysis, spectra detection, and vibrational temperature calculation, it was concluded that the exothermic chemical reactions occurring at around 25 ms in plasma were closely correlated to the macroscopic detonation processes, which is consistent with published results stating that the exothermic chemical reactions occur between 12 to 100 ms aer pulsed lasers loading. 13,31 3.4 High-accuracy detonation parameters prediction by SVR Consequently, we collected some typical 25 ms delayed laserinduced plasma images that carry explosion information on the exothermal chemical reaction of all samples, as input for the quantitative analysis model of detonation parameters to establish the prediction characteristic functions. In this work, SVR with the solver of sequential minimal optimization (SMO) was adopted to determine the detonation performance, and the algorithm ow chart is shown in Fig.…”