Ultraviolet Laser-induced ignition of RDX single crystal.

Zhonghua Yan,Chuanchao Zhang,Bisheng Tan,Xiaotao Zu,Xuming Wang,Wei Liu,Zhijie Li,Li Li,Hongwei Yan,Xiaodong Yuan,Zongwei Yang,Ming Huang,Jinshan Li,Guorui Zhou

doi:10.1038/srep20251

Abstract

The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

Highlights

The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses
As the laser fluence increases, damage area of “S1” increases firstly, and remain in an approximately constant value when the laser fluence is over 12 J/cm[2]
The (210) crystal facets of secondary explosive RDX single crystals were ignited by ultraviolet laser (355 nm, 6.4 ns) pulses with fluences above the laser-induced breakdown threshold of 1.7 J/cm[2], and their damage growth manners were characterized in detail

Summary

Introduction

The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. Ali et al utilized CO2 laser ignition experiments[10] to figure out the reactive mechanisms of HMX and TATB during deflagration-to-detonation transitions. Additives, such as MgO particles[11], carbon black[12,13], Al ultradispersed particles, Ni-C and Al-C mechanocomposites[14], etc. Most of the energetic materials used in their works were explosive powders or micro-crystals pressed into tablets or pellets at some pressure. In these traditional sample preparation methods, the chaotic configuration of explosive crystals makes it impossible to establish quantitative investigations on the laser ignition dynamics in aspect of crystallography discrimination. Et al.[18] and Ming-Wei Chen, et al.[19] have explored the fundamental mechanisms of hot spot generation with Nd/glass laser (pulse width of 300 μ s) and CO2 laser, respectively

Methods

Results

Conclusion