Observations of thermal response of energetic materials

Abstract

In this paper, we review the current state of our understanding of the thermal response of secondary high explosives and describe the lab-scale X-ray radiography techniques we have developed to observe explosives behavior. The thermal response of explosives can range from slow thermal decomposition over hours at temperatures below the critical temperature up to nanosecond detonation reaction zones at temperatures of thousands of degrees. We have attempted to follow the evolution of the thermal response of secondary high explosives covering this entire range of temperatures and resulting times. In doing so, we have found that there are several switches accelerating the time scales from thousands of seconds to nanoseconds. We have found it helpful to develop a diagram showing the multiple switches taking the material from initial solid state to the final working fluid in a detonation. In order to follow this evolution through observations and measurements, we have developed a number of diagnostic tools capable of covering the wide dynamic range of the problem. In this paper, the X-ray radiography diagnostic will be discussed in detail and others referenced. The measurements taken during the application of boundary conditions and the explosive response are incorporated into a theory and modelling effort results of which will be utilised here with details described elsewhere[1].