Kinetics of carbon clustering in detonation of high explosives: Particle growth along hydrodynamic streamlines

Chemical reactions in detonation of carbon-rich high explosives yield solid carbon as a major constituent of the products. Efforts to theoretically describe the kinetics of carbon clustering go back to the seminal paper by Shaw and Johnson, where it was modeled as a diffusion-limited irreversible coagulation of smaller clusters into larger ones. In this talk, we will discuss recent direct experimental observations of carbon cluster growth in detonation of high explosives, based on time-resolved small-angle X-ray scattering (TR-SAXS). We will focus on comparison of these results with calculations based on (i) realistic hydrodynamic modeling of detonation of PBX 9502 high explosive, (ii) the Shaw-Johnson model of carbon particulate growth along the streamline obtained from the hydrodynamic simulations, and (iii) accurate simulations of the TR-SAXS signal. We demonstrate that this three-step simulation approach agrees well with the recent experimental results. The implications of this agreement on our present understanding of in-detonation carbon clustering processes will be discussed.