Possibility of population inversion by ultraviolet optical pumping

A study is made of the possibility of a population inversion as a result of the 1s2p³P→1s² transition in He-like ions of the elements with z = 6–15. The ions accumulate in the upper state 1s2p³P as a result of optical pumping of an active medium containing Li-like ions by radiation from a laser plasma followed by a spontaneous transition to the ground state. The wavelength of the radiation due to this transition is 0.6–4.1 nm and the gain is 10^–2 cm^–1. A study is made of the possibility of increasing the gain by compressing the active medium.