Laboratory-Scale Method for Estimating Explosive Performance from Laser-Induced Shock Waves

Abstract

A new laboratory-scale method for predicting explosive performance (e.g., detonation velocity and pressure) based on milligram quantities of material is demonstrated. This technique is based on schlieren imaging of the shock wave generated in air by the formation of a laser-induced plasma on the surface of an energetic material residue. The shock wave from each laser ablation event is tracked for more than 100 μs using a high-speed camera. A suite of conventional energetic materials including DNAN, TNT, HNS, TATB, NTO, PETN, RDX, HMX, and CL-20 was used to develop calibration curves relating the characteristic shock velocity for each energetic material to several detonation parameters. A strong linear correlation between the laser-induced shock velocity and the measured performance from full-scale detonation testing has been observed. The Laser-induced Air Shock from Energetic Materials (LASEM) method was validated using nitrocellulose, FOX-7, nano-RDX, three military formulations, and three novel high-nitrogen explosives currently under development. This method is a potential screening tool for the development of new energetic materials and formulations prior to larger-scale detonative testing. The main advantages are the small quantity of material required (a few milligrams or less per laser shot), the ease with which hundreds of measurements per day can be obtained, and the ability to estimate explosive performance without detonating the material (reducing cost and safety requirements).