Inversion of level populations in H-like fluorine ions in a recombining laser plasma

Inversion of the populations of the n = 5,4, and 3 levels of hydrogen-like F ix ions in a recombining laser plasma was studied. The calculated values of the gain were 10^–2–10^–1 cm^–1 and these agreed with estimates based on measurements of the absolute intensities of the spectral lines representing spontaneous emission. Geometry of expansion of a plasma jet was studied.