Modeling of ignition of organic explosives by a laser pulse in the weak absorption range

Ignition of RDX, HMX, and TATB by a nanosecond laser pulse is numerically simulated. The heat conduction equation in a cylindrical coordinate system is solved with allowance for multiple reflections of the light beam, zeroth-order exothermic reaction, and melting. Despite a small temperature gradient caused by a small coefficient of radiation absorption, violation of thermal equilibrium due to the Arrhenius nonlinearity leads to ignition of energetic materials from the surface. The critical energy density of PETN, RDX, HMX, and TATB ignition by a nanosecond laser pulse is determined. For identical absorption and reflection coefficients, the calculations show that the most sensitive explosive is PETN, whereas the most heat-resistance explosive is TATB.