We give on overview of recent advances in collisionally pumped optical field-ionization soft X-ray lasers developed at LOA. Saturated amplification has been achieved on the 5d-5p transition in Xe8+ at 41.8 nm, and on the 4d-4p transition in Kr8+ at 32.8 nm. We demonstrate a significant increase of the energy output from the Xe8+ laser driven within two types of wave-guide. Finally, we present results of a pioneering work aimed to set up and characterize the first true soft X-ray laser chain.

Polycrystalline lithium fluoride thin films have a number of existing and potential uses, but the optimization of their microstructure has not yet been addressed systematically. We have developed a means of measuring the porosity in LiF films, and a method for performing detailed electron-microscopical studies on this normally beam-sensitive material. These techniques have been applied to assess the structure of LiF films immediately after deposition from the vapor phase, and also after subsequent annealing.

We address the problem of the preferential mode excitation in magnetic Ap-stars by estimating the pulsation energy losses in the atmosphere through the generation of the Alfvenic waves.

We consider the synthetic power spectra of multi-mode solar-type acoustic oscillations in stars, computed within a general framework of the linear response of the dynamical system to an arbitrary excitation force which is decomposed in spherical harmonics in space and harmonic functions in time. We discuss possible signatures in the observational data which might be used as diagnostics of the excitation source.

We report the results of a nonlinear inversion of solar oscillation data that enable us to detect nonideal Coulomb interactions between particles, including pressure ionization, in the solar convection zone.

Rotation and a magnetic field break the spherical symmetry of a star viewed as a pulsating system, lifting the degeneracy of oscillation frequencies, and leading to (sometimes prominent) observational consequences. Theoretical studies of rotational and magnetic effects in pulsating stars are reviewed, starting with simple configurations with slow rotation and weak magnetic fields.

The asymptotic inversion technique is developed, including independent determination of the sound speed profile and frequency dependence of the effective phase shift. Numerical results are presented.

An overshoot region near the base of the solar convection zone may be the region where intense magnetic fields are stored during the solar cycle (Spiegel and Weiss, 1980; Schmitt and Rosner, 1983; Pidatella and Stix, 1986). In this report we study the possible influence of such a field on the frequencies of the solar five-minute oscillations.

Perturbation theory is developed for calculating the influence of slow differential rotation on the adiabatic nonradial modes of stellar oscillations. The effects of Coriolis forces and ellipticity are analysed simultaneously using the perturbation technique for Hermitian operators which is developed up to second order in eigenvalues and to first order in eigenvectors.