Initiation of PETN Powder by Pulse Laser Ablation

We developed a laser‐driven method of initiating a secondary high explosive charge, based on the energy conversion from the pulsed laser energy to the shock wave energy. Enhanced energy conversion was found from optical to mechanical by an intentionally roughened surface of a transparent medium through which laser beam propagates. In this study, a PMMA plate is used, one of whose surface was intentionally roughened. Aluminum coating of less than 1 μm thickness was made to further enhance the laser absorption at the surface. Observed air shock wave indicates that it is very strong with Mach number larger than 30. Nd:YAG laser of 4 ns duration, 1064 nm wavelength and of up to 200 mJ was used as an energy source. Detonation emission of PETN powder was recorded by an image converter streak camera. Delay of 200–300 ns in the initiation was detected.