Atmospheric effects on the laser-driven avalanche-based remote detection of radiation

The effect of realistic atmospheric conditions on mid-IR (lambda = 3.9 mu m) and long-wave-IR (lambda = 10 mu m) laser-induced avalanche breakdown for the remote detection of radioactive material is examined experimentally and with propagation simulations. Our short-range in-lab mid-IR laser experi-ments show a correlation between increasing turbulence level and a reduced number of breakdown sites associ-ated with a reduction in the portion of the focal volume above the breakdown threshold. Simulations of propaga-tion through turbulence are in excellent agreement with these measurements and provide code validation. We then simulate propagation through realistic atmospheric turbu-lence over a long range (0.1-1 km) in the long-wave-IR regime (lambda = 10 mu m). The avalanche threshold focal volume is found to be robust even in the presence of strong turbu-lence, only dropping by-50% over a propagation length of-0.6 km. We also experimentally assess the impact of aerosols on avalanche-based detection, finding that, while background counts increase, a useful signal is extractable even at aerosol concentrations 105 times greater than what is typically observed in atmospheric conditions. Our results show promise for the long-range detection of radioactive sources under realistic atmospheric conditions.(c) 2023 Optica Publishing Group

Automated summary

This paper experimentally and simulates the effect of realistic atmospheric conditions on mid-infrared (lambda = 3.9 μm) and long-wave infrared (lambda = 10 μm) laser-induced avalanche breakdown for remote detection of radioactive material. The experimental results show that increasing turbulence levels are correlated with a reduction in the number of breakdown sites and the portion of the focal volume above the breakdown threshold. Propagation simulations through turbulence validate these measurements. In the long-wave infrared regime (lambda = 10 μm), simulations show that the avalanche threshold focal volume remains robust even in the presence of strong turbulence, with only a 50% drop over a propagation length of 0.6 km.