EXPERIMENTAL-STUDY OF CO2-LASER-INDUCED AIR BREAKDOWN OVER LONG DISTANCES

Results of an experimental study on air breakdown produced by radiation from a high-power CO2 laser are presented. From these measurements, the breakdown threshold over a flux range (1.5×108 <φ<7×108 W cm-2) is obtained as a function of the focal length varying from 1 to 55 m. The first of these experiments was carried out in the laboratory atmosphere (10<f/D<100), whereas the second part (f/D=135) was done outdoors under typical atmosphere conditions. The temporal evolution of the energy transmitted through the breakdown region for different laser parameters (5<Ei<220 J) was found.