Single-frequency oscillation of a wide-aperture krypton laser

The parameters of a high-current krypton discharge in tubes of an increased diameter (5 – 7 mm) are studied and optimised. Increased lasing power on the lines of singly and doubly charged krypton ions is achieved: 14 W (647 – 676 nm) and 6 W (407 – 415 nm). One transverse and one longitudinal mode are selected with efficiencies of 85 and 70 % using a convex – concave resonator and a Fabry — Perot etalon, respectively. The shape of the Lamb dip at the 676-nm line is studied in the single-frequency oscillation mode. It is shown that, in accordance with the theory, the dip broadens by a factor of 2.6 due to Coulomb ion – ion collisions at an achieved electron concentration N_e ~5 × 10¹⁴ cm^-3.