This volume of the LLE Review covers the three-month period January--March 1993. The OMEGA laser facility was decommissioned during this quarter to make room for the OMEGA Upgrade laser facility. The decommissioning is described in this volume. Electron thermal transport in the corona and laser-irradiation uniformity are related issues for direct-drive laser fusion. Thermal transport can affect the laser-irradiation uniformity requirements. The status of Fokker-Planck modeling of electron transport at LLE is reviewed and is followed by a description of a new technique for achieving high laser uniformity using zero-correlation phase masks. The use of fast, optically triggered, superconducting opening switches can, in principle, reduce the peak electrical load requirements of systems like the OMEGA Upgrade. Recent research in this area is described. The last three articles discuss vacuum ultraviolet and x-ray emission from short-pulse, laser-matter interactions. The generation of a high spectral brightness, picosecond K{alpha} source is described. The subsequent articles describe the generation of high-order harmonics of a high-intensity laser system laser system in low- density, laser-atom interactions and the novel gas target used.

This volume of the LLE Review, covering the period April--June 1993, contains articles on spectral features from argon-filled target implosions on OMEGA, and on the theory of an implicit difference scheme for the Fokker-Planck equation. The advanced technology section includes reports on a novel polymer liquid-crystal wave plate and a new scheme for phase conversion of the OMEGA Upgrade beams that results in greater, smoother energy deposition on fusion targets. Finally, reports on the as-designed configuration of the OMEGA newly configured glass development laser system are summarized.

This volume of the LLE Review, covering the period July--September 1993, contains articles on self-focusing of broad-bandwidth laser light with angular dispersion, laser patterning of thin-film circuits, and construction of foam-shell fusion targets. Reports on the detailed designs of major subsystems of the OMEGA Upgrade and on the continuing activation of the upgraded Glass Development Laser system are summarized. Descriptions of research proposals for NLUF are also included in this issue. Highlights of the research reported in this issue are: Previous investigations of self-focusing behavior of broad-bandwidth laser light without angular dispersion showed only slight differences when compared to laser light with angular dispersion. A new, numerical investigation of self-focusing with applied angular dispersion shows the development of transverse amplitude modulation, which can act to enhance or impede instantaneous self-focusing. Averaging over one period of phase modulation with imposed bandwidth shows consistent smoothing of the beam, nearly replicating the original spatial profile, including smoothing of induced perturbations due to laser-system imperfections. A continuous-wave argon-ion laser beam is focused onto a Y-Ba-Cu-O thin-film circuit. The laser beam selectively heats the epitaxy, which enriches oxygen in irradiated regions alongside depleted regions. Oxygen enrichment results in the formation of superconducting regions, while oxygen …

During this quarter, the visible fruits of long design labors on the OMEGA Upgrade began to appear. The target mirror structure was put in place, along with the target chamber itself. The laser bay structures were also installed, and the bay is now being prepared to receive optomechanical, control, and laser assemblies. Further details are in the OMEGA Upgrade Status Report in this issue. Theory and analysis of previous experiments continued during this reporting period. Articles contained herein describe an improved theory of the ablative Rayleigh-Taylor instability; a novel proposal for characterizing plasma-density profiles by using grid image refractometry; a much-improved treatment of the damping of ion sound waves in a mixture of light and heavy ions; and, finally, a new interpretation of measurements of 3/2-harmonic radiation emitted from the long-scale-length plasmas created in earlier OMEGA experiments.