Kinetic model of the active medium of a He — Ar laser pumped by a hard ioniser

Abstract

A detailed nonstationary model of a He — Ar laserpumped by a hard ioniser is developed. It is found by numerical simulation that the pumping of the upper laser level isgoverned either by the three-body recombination of atomicargon ions with electrons or the dissociative recombination ofmolecular argon ions with electrons, depending on the argoncontent in a gas mixture. The conversion of dimer molecularargon ions into trimers, the quenching of the upper laser levelby neutral atoms, and the spectral line broadening determinethe optimum lasing conditions for the total mixture pressureand the partial argon pressure for different excitation conditions. The model adequately describes experiments usingelectron beam and nuclear pumping. The optimisation of a1.79-μm nuclear-pumped He — Ar laser in the VIR-2M reactor gave a maximum laser efficiency of 1.2 %.