Quantitative correlation between facets defects of RDX crystals and their laser sensitivity

Area of Science:

• Materials Science
• Physical Chemistry
• Laser Physics

Background:

• Cyclotrimethylenetrinitramine (RDX) is a high explosive.
• Understanding RDX sensitivity is crucial for safety and performance.
• Surface properties can influence material reactivity.

Purpose of the Study:

• To investigate the relationship between surface defects on RDX {210} facets and laser sensitivity.
• To quantify the correlation between surface roughness and laser ignition.
• To elucidate the physical mechanisms behind laser-induced ignition of RDX.

Main Methods:

• Scanning electron microscopy (SEM) and atomic force microscopy (AFM) for surface characterization.
• Direct laser ignition tests using a 355nm UV laser with a 6.4ns pulse width.
• 3D Finite-Difference Time-Domain (FDTD) simulations to model light-matter interactions.

Main Results:

• RDX laser sensitivity is strongly correlated with the surface roughness of its {210} and {2¯1¯0} facets.
• Surface defect sizes comparable to the laser wavelength significantly affect sensitivity.
• FDTD simulations confirm that micro-defects modulate laser intensity, explaining the observed sensitivity correlation.

Conclusions:

• Surface morphology, specifically roughness at the scale of the laser wavelength, is a critical factor in RDX laser sensitivity.
• Microscopic surface defects play a key role in initiating laser-induced ignition of RDX.
• The findings provide insights into the fundamental mechanisms of energetic material laser sensitivity.