Experimental investigation of population inversion of oxygen K-ion levels

Experimental results are reported of investigations of the optical properties of the plasma produced when an AI₂O₃ target is irradiated in vacuum by a high-power neodymiunr-glass laser system. It is shown that a number of 0 VIII and 0 VII ion levels with principal quantum numbers n = 2, 3, 4 are inversely populated. The gain at the wavelength 29 nm (4 3 transition, O VIII) under the experimental conditions is of the order of 0.01 cm^-1. For the heliumlike ions O VII, in a transition with the same principal quantum numbers (ls4p¹P₁ ls3s¹S₀, 36.9 nm), the gain is of the order of 10^-2–10^-1 cm^-1, depending on the electron density.Translated from Lazernye Sistemy, pp. 5–14 1982.