Effect of the microfocal nature of the initiation of the explosive decomposition reaction on the efficiency of laser initiation

A microfocal-mode model of the initiation of the chain reaction of explosive decomposition during the laser initiation of energetic materials is proposed. Reaction microfoci arise from excitation density fluctuations as a result of the stochastic nature of the interaction of photons with the energetic material during photoinitiation. The explosion probability is determined by two competing processes: (1) the micro-explosion of an isolated microfocus, resulting in the ejection of material from the microfocus area to form a cavity and (2) the overlapping of growing microfoci, a process leading to the formation of an explosion zone and the macro-explosion of the entire sample or its substantial part. Model predictions (dependence of the explosion probability and the duration of the induction period for PETN initiation on the fluence (1064 nm, 10 ns)) are experimentally verified, confirming the adequacy of the proposed model.