Influence of the Density of PETN-Coal Composites on the Threshold Characteristics of Explosive Decomposition in Laser Initiation

This paper presents the results of measuring the thresholds of explosive decomposition of PETN-coal under the action of laser radiation pulses (lambda = 1064 nm and tau = 14 ns). Samples whose thickness is 1 mm and whose densities are 1.1 and 1.7 g/cm(3) with inclusions of submicron particles of brown coal (750 nm) are investigated. Matrices in composites with densities of 1.1 and 1.7 g/cm(3) are almost transparent for radiation. A minimum explosive threshold of 1.8 J/cm(2) is reached with a concentration of inclusions of 0.5% (by weight). The explosion is adiabatic. Composites with a density of 1.1 g/cm(3) have a scattering matrix. A minimum explosive threshold of 2.3 J/cm(2) is obtained for a concentration of inclusions of 1%. An extinction rate is estimated: k(ext) = 135 cm(-1). Radiation is absorbed at a depth of <0.1 mm. Explosive decomposition in an unirradiated section develops according to the shock-wave mechanism of explosive combustion.