Modeling of table-top transient inversion and capillary X-ray lasers

Numerical modeling of transient inversion and capillary discharge X-ray lasers were performed for the purposes of understanding of recent experiments, improving the laser efficiency and planing their further development. The first demonstration of saturation of a low pump energy X-ray laser utilizing a transient inversion mechanism on the 3p-3s transition at 32.63 nm in Ne-like Ti has been confirmed. A close to saturation amplification was simultaneously achieved for the 3d-3p, J=1-1 transition at 30.15 nm. Small signal effective transient gain coefficients of g similar to 46 cm(-1) and similar to 35 cm(-1) and effective gain-length products of 16.7 and 16.9 for these lines were obtained. Experiments and calculations demonstrate that it is possible to achieve saturated laser action in a transient regime with Ne-like Ti for a pump energy as low as similar to 5 J. With such energies just recently the lasing on Ni-like Pd at 14.7nm has been achieved. MHD simulations of capillary discharges were performed for several elements with shorter lasing wavelengths. A new approach which intends to combine advantages of electrical discharge plasma preparation with CPA-laser excitation was investigated. It will enable a kind of X-ray lasers to be built with ultrashort pulse duration and the high efficiency. In this case the well preformed cylindrical shell of discharge plasmas and the transient population inversion combined with the traveling-wave excitation will enable to achieve lasing at much shorter wavelengths.