Photoionization in pulse CO2 laser

Measurements were made of the density of photoelectrons in He, N₂, and CO₂–N₂–He mixtures created by a planar ultraviolet radiation source ensuring a bulk discharge in a real CO₂ pulse laser. The experiments and calculations demonstrated that the photoelectron density in laser mixtures and its behavior as a function of the distance from the ultraviolet radiation source were governed by the ionization of impurities with low ionization potentials present in the gas and by the absorption of the radiation in the CO₂ molecules. Introduction of optimal numbers of such impurities (xylene and dimethyl aniline) made it possible to increase the photoplasma density by more than one order of magnitude; under these conditions the photoplasma decayed by recombination at a rate represented by the recombination coefficient 10^–5 cm³sec^–1.