Study of the Influence of Atmospheric Air on the Active Medium of an Optically Pumped Rare Gas Laser

This paper presents a theoretical study of the influence of atmospheric air impurity on the active medium of an optically pumped rare gas laser. The active medium of the laser is formed by passing a pulse-periodic discharge through an argon–helium plasma and represents excited states of argon at the lower levels of the s- and p-multiplets. The analysis of key reactions of the interaction of nitrogen and oxygen particles with each other, with electrons, and with argon and helium atoms is carried out. The key reactions of interaction that have the greatest effect on the particle concentration are selected. A kinetic model of Ar–He plasma is compiled and the reactions of the interaction of inert-gas atoms with nitrogen and oxygen atoms, molecules, and ions are added. The concentration of excited argon atoms and other plasma particles is calculated. The calculation results demonstrate that when the proportion of impurity gases in the active medium of the laser exceeds 1 × 10−5, their effect on the concentration of excited argon and helium atoms and ions becomes noticeable. When the proportion reaches 5 × 10−4, the quenching of excited atoms due to collisions with nitrogen and oxygen begins to prevail over other quenching mechanisms.