Heating of metals by CO2 laser radiation pulses

An experimental study was made of the heating of metal targets by CO₂ laser pulses of intensity 1–100 MW/cm² at various air pressures (10^–5–1 atm). Initiation of breakdown in the vapor of the target material or of low-threshold breakdown in air increased considerably the deposition of the laser energy in the target. A size effect was then observed: the effective absorptivity of metal targets increased when the ratio of their radius to the radius of the illuminated spot was made larger. The results were explained by the contact of the breakdown plasma with the target surface in the course of the former's expansion into the ambient medium.