Thermal explosion and the theory of its initiation by steady intense light

Abstract

The initiation of explosion by steady intense light (from lasers or other sources) involves degradation of the radiation to heat, leading to self-heating and thermal runaway. The critical conditions for such a thermal mechanism can still be expressed in terms of the standard dimensionless group δ = qσ a 0 2 AEexp ( -E/RT a )/ k RT a 2 . When δ attains a critical value δ cr , thermal explosion occurs: the critical value depends on the intensity of the radiation. The dependence of δ cr on the light intensity β is computed numerically for an Arrhenius temperature-dependence of rate. The corresponding critical values for the reduced central temperature-excesses θ 0 , cr are also obtained. If the ambient temperature is too high or the activation energy is too low, so that є = RT a /E is not very small, the phenomenon of criticality disappears. Accurate transitional values for the reduced ambient temperature є tr are calculated as a function of the intensity of the light.