Initial Thermal Response of Micro/Nano-Al particle Embedded in Energetic Materials Excited by Single-Pulse Laser

Abstract

The incorporation of Al particles into explosive formulations has been a subject of ongoing interest because the Al particles can increase the energy content of explosives and tailor the energy release rate. The initial thermal response of micro/nano- spherical Al particles embedded in energetic materials excited by single-pulse laser is investigated by several models, which is crucial for understanding and controlling the thermal ignition mechanism of energetic materials. The thermal relaxation dynamics of electron and lattice in Al particle excited by short pulse (ps) laser are described by the two-temperature model. The characteristics of thermal diffusion of micro/nano-Al particle to the particle environment are analyzed using Fourier law for the long pulse (ns) laser. The influences of laser energy and pulse duration on the thermal response are also examined. The results show that, the thermal diffusion is very important for nano-Al particle during the pulse passage. It can cause the rise of temperature of surrounding energetic materials and thus form the “hot spot” with high temperature and large scale. That can shorten the time of ignition and enlarge the region of ignition. The laser energy and pulse duration are determined to effectively regulate the temperature and size of “hot spot” caused by the nano-Al particles, and the concrete relationships among them are obtained. These results are expected to be a useful indication for adjusting laser ignition (initiation) properties of aluminized explosives by selecting suitable parameters such as particle size, laser pulse duration or laser energy in experiment and practical application.