Sc-Si multilayers are suggested as high-reflectivity coatings for a VUV interval of 35-50 nm. Fabricated mirrors show normal-incidence reflectivity of 30-54%, which is high enough for effective manipulation of the beams of compact-discharge, laser-driven x-ray lasers. The values obtained are not, however, limits for Sc-Si coatings. Theoretical estimations as well as electron microscopy studies of Sc-Si interfaces indicate a large potential for a further increase in their reflectivity.

The transition array 3d2-3p3d has been identified in the spectra of magnesium-like ions produced by laser irradiation on the eleven elements from K to Cu. The results confirm and extend earlier analyses, the terms 3d2 3P and 1S being found in several ions. These data are used for a theoretical interpretation of the 3l3l' configurations by means of the Slater-Condon method with generalized least-squares fit for the parameters. Predicted spectra are given for Ga XX-Br XXIV and the earlier analysis of Kr XXV is revised and extended.

The transition arrays 3p3, 3s3p3d-3p23d, 3s3d2 have been identified in the spectra of aluminium-like K VII-Ni XVI ions, excited in a laser-produced plasma. On the basis of this identification the energies of the essential part of the levels of the 3p23d and 3s3d2 configurations and the 3s3p3d4F term have been determined for the first time in these ions. The identifications are supported by the multiconfiguration Hartree-Fock calculations.

The thermal stability of Mo-Si multilayers prepared by magnetron sputtering is studied. It is found that degradation of x-ray reflectivity of Mo-Si multilayers under heat loading is connected with the roughening of Mo-Si interfaces and the formation of compounds Mo(x)Si(y),. To avoid these degradation mechanisms we fabricated and tested MoSi(2)-Si multilayers under heat loading. The MoSi(2)-Si multilayer appeared to be much more stable both in period and x-ray reflectivity because of thermodynamic equilibrium of the components MoSi(2) and Si at the interface. The working temperature of MoSi(2)-Si multilayers reaches 1000 K.

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