Coulomb broadening of a Lamb dip of an Ar2+ laser

Expressions for the calculation of the profile of a Coulomb-broadened Lamb dip are proposed for the case of a high-power single-frequency ion laser. Measurements are reported of the width of a Lamb dip in the ultraviolet radiation emitted by an Ar²⁺ laser. Strong Coulomb broadening of 1600 MHz (compared with 400 MHz in the case of singly ionized ions) confirms a strong influence of the ion charge on the width of the dip. Estimates are obtained of the concentrations of singly and doubly charged ions. It is shown that these concentrations become comparable at the stability limit of a discharge.