Atomic Weapons Establishment (AWE)

The Atomic Weapons Establishment (AWE) is a centre of scientific and technological excellence, with some of the most advanced research, design and production facilities in the world. Commencing from the 1950.s, AWE has been committed to the manufacturing and maintenance of the UK.s nuclear deterrent. Whilst ensuring the country.s safety and security, AWE fully supports and adheres to the Comprehensive Test Ban Treaty and counter terrorism.

Hydrodynamics is based on the conservation laws of mass, momentum and energy. At high pressure and stress levels, even materials such as metals change volume and shape readily and flow in a manner similar to a fluid. Prediction of the dynamic behaviour of materials as they flow under the influence of high pressure and stress is of considerable importance in the understanding of weapons. Simulations of the hydrodynamic behaviour of experiments are carried out on AWE.s supercomputers using calculations known as hydrocodes. The results from these simulations are verified with experimental measurements.

The regimes of interest are shock wave conditions, ranging in pressure from a few tens of kilobars (Kb) up to several megabars (Mb). (1 Kb is roughly the pressure at the bottom of a mid-ocean trench. The pressure at the centre of the earth is around 3 Mb). In order to understand how the effects of explosive materials work in a physical sense, we must first understand how waves are formed and how different types of waves can have different effects.

Explosive materials and detonators propagate waves through solid matter and gas. During the detonation process of an explosive, large volumes of gas are given off in the chemical reaction. Due to the speed of the reaction, a shock wave is created which precedes the chemical reaction.

It is therefore not only important to understand how waves (sound and shock) impact upon materials used in weapon design, but also how the pressure of an explosive event impacts upon the surrounding environment.

This presentation will consider the aspects involved in wave theory, giving practical demonstration of waves and pressure.