A novel technique for the controlled initiation of explosives

Abstract The observation that the jet initiation of covered and bare explosive occurs by quite different mechanisms has been used to devise a novel technique for producing either prompt detonation at a predetermined position within an explosive charge or failure and disruption. The method consists of firing a jet at an appropriately covered explosive containing a void located where the onset of detonation is required. The void contains a low density medium to dissipate the bow wave shock and may be positioned within the bulk of the explosive or on the surface. When the jet strikes the far side of the void prompt detonation occurs and spreads throughout the explosive. However, when the jet is aimed to miss the void, failure occurs. The technique is described in detail and illustrated by flash radiographs showing both the detonation and failure modes for a Composition B charge containing a spherical void located near its center. For Composition B the estimated maximum depth of locating the void, and therefore the point of initiation, is approximately 320 mm from the charge surface. Potential applications and some limitations of the method are discussed. The technique is the subject of patent action.