Development of laser driven detonator assembly for detonation of insensitive explosives

The conventional method used for detonation of explosives is electrical transmission. Electrical detonators are not safe as they depend on the principle of firing of sensitive primary explosives, which are highly sensitive to impact, heat, shock, electrostatic discharge and electromagnetic effects. System safety and performance can be provided at high levels due to isolation of the explosive from the external electrical effects when the detonation is achieved by heating the explosive with a laser beam instead of using electrical transmission. For this reason, laser detonators are amongst the safest ignition systems. In the thesis study, a laser driven flying plate system was developed, a prototype was manufactured, and shock-induced detonation of insensitive explosives was performed. Within this scope: - Laser firing unit was designed and installed. It was found that the beam obtained from the laser power unit at 100% peak value could reach the target with 25% loss. - An igniter body that contains the energetic material, where the laser beam is transmitted, was designed and manufactured. The body, in which the flying plate was placed, was manufactured using a design from literature. - HMX, an insensitive explosive, was adapted to the laser beam. Within the scope of improving the optical properties of HMX, a special sample preparation method was developed for its homogeneous mixing with carbon black. - The laser firing system was tested using the samples containing HMX. - The production of the detonator prototype was finalized by integrating the flying plate body to the laser driven igniter body. In the design of this prototype, the rupture pressure was calculated as 420 MPa for the PMMA plate and 198 MPa for the Al plate. - Performance studies of the prototype was carried out in a 10 cm3 closed bomb system using 1.32 g/cm3 low density HMX and a 400 µm thick plate: The ignition pressure and the velocity of the plate were measured as 48.4±1.6 bars and 620±58 m/s, respectively. - A mathematical model was developed to predict the plate velocity. The plate velocity was calculated as 667.27 m/s and within the measured 562-678 m/s interval for the same operating conditions. It was calculated that the exit velocity of a 0.2 mm thick Al plate from a system with a 14 mm long acceleration gap could reach a much higher speed of 1.4 km/s. This study comprises the domestic development of a safer detonation system due to the application of a lazer triggering system for direct detonation of insensitive explosives based on the flying plate method. It has formed a basic R&D study for laser detonators that can be used commercially in military munitions, such as rocket engines and warhead igniters. Keywords: Laser driven flying plate, detonator, insensitive explosives, shock to detonation transition, mathematical modelling, flying plate velocity