Dependence of Energy Thresholds on Laser Radiation Wavelength in Initiation of Heavy Metal Azides

TL;DR

This study investigates how laser wavelength affects the energy needed to initiate explosive decomposition in heavy metal azides, revealing significant dependence at certain wavelengths and the influence of surface covering on thresholds.

Contribution

It provides new insights into the dependence of initiation energy thresholds on laser wavelength and surface conditions in heavy metal azides.

Findings

Thresholds vary with laser wavelength and surface coverage.

Covering with a transparent plate affects thresholds in bandgap absorption region.

Gas-dynamic unloading influences initiation energy thresholds.

Abstract

The behavior of silver and lead azides (scaly and threadlike crystals, and compacted powders) in initiation of explosive decomposition by laser pulsed radiation has been investigated. Initiation energy thresholds in irradiation at wavelengths of 1064 nm, 532 nm, 354.7 nm, 266 nm corresponding to four laser radiation harmonics have been measured. Samples both uncovered and covered with a transparent dielectric (a quartz plate) with the compressive force of up to 0.5GPa were initiated. In the transparent spectral region (the first and second laser harmonics) of the heavy metal azide matrix the effect of covering the sample surface with a plate on initiation energy threshold was insignificant, whereas, in the region of bandgap absorption (the fourth harmonic) strong dependence of the initiation threshold on whether the surface under irradiation is uncovered or covered. The results obtained have been considered with the account of the influence of the transparent plate on gas-dynamic unloading of the thermal site, which is formed in the bandgap absorption of laser radiation in a thin near-surface layer.