Initiation of a reactive material by a radiation beam absorbed by optical heterogeneities of the material

The heating dynamics and thermal ignition of a condensed transparent material by a radiation pulse absorbed by optical micro-heterogeneities present in the material were studied numerically and approximately analytically over a wide range of pulse durations. For quasistationary heating conditions of micro-heterogeneities, an analytical dependence of the radiation power density critical for ignition on the formal kinetic parameters of the chemical process and the radius of the particle absorbing the radiation was obtained. The critical energy characteristics of ignition are compared with experimental data on the initiation threshold of lead azide by laser pulses of different duration.