Feasibility of using one coincidence of the wavelengths of the spectral lines of the pump radiation and active medium in the VUV range

A theoretical study is reported with the feasibility of population inversion as a result of transitions in the oxygen ion O III pumped by a resonant line of the He II ion (λ = 30.4 nm). These calculations are based on a radiative–collisional model. Coincidence of the pump and active medium wavelengths can be achieved by utilizing the ³He II isotope. A population inversion then occurs for a series of the 3–3 transitions in the O III ion. When the electron density is N_C ~10¹⁶ cm ^– 3 and the electron temperature is T_e ~3–4 eV, the gain at the λ = 344.4 nm wavelength is k_ω ~ 0.1–1 cm ^– 1.