Optical breakdown threshold of air near a polished metal surface for λ = 10.6-μ radiation

An investigation was made of the conditions for the formation of an optical breakdown plasma in air when CO₂ laser radiation interacted with a polished metal surface in the case of two strongly differing widths of the irradiation spot. Metallographic investigations were made of the surface of the irradiated samples. For the first time, the specific form was established of the surface defects which lowered the breakdown thresholds.