Simulation of the population inversion at hydrogen-like FIX and LiIII ion transitions in a recombining laser plasma

Spatial distributions of the intensities and inversion factor of the F IX i on lines of the Lyman series are studied as functions of the irradiation co nditions, Laser plasma was produced by the first-harmonic radiation from a Nd laser (10-35 J, 0.6 ns) focused on a flat solid target. It is shown that , for moderate intensities (approximate to 10(14) W/cm(2)), the use of phas e plates, which smooth spatial beam inhomogeneities on the target, results in an appreciable increase in size of the emission region of recombining F IX ions. The experimental data are compared with calculations by the "Ion" computer code. Experiments on forming an extended active medium for lasing at the 4-3 transition of the hydrogen-like lithium ion are numerically simu lated. This transition, having a wavelength of 208 nm in the UV spectral re gion, affords the inversion pickup using a resonator with available highly reflecting Al+MgF2 mirrors.