Initiation of PETN detonation by an impactor and a high-enthalpy gas flow

This paper compares two methods of near-threshold initiation of a loose-packed PETN charge: by impact of a plate and by injection of an intense flow of hot gases into the powder. Synchrotron diagnostics of material density was used. Both methods lead to the development of detonation in about 10 $\mu$s, but the nature of initiation differs sharply. Initiation by an impermeable piston involves the formation of a dense plug of compressed material. After some delay, a wave is formed at the front of this plug which initiates chemical reaction and accelerates to normal detonation. For high-enthalpy initiation by a hot gas flow, the compression of the powder is low and the process develops in the gas-permeable material, starting from the stage of rapid convective combustion followed by transition to detonation.