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LLE Review, Quarterly Report: Volume 61, October-December 1994 (open access)

LLE Review, Quarterly Report: Volume 61, October-December 1994

This volume of the LLE review, covering the period of October--December 1994, contains articles on a diagnostic method employing krypton spectroscopy for measurement of temperature and shell-fuel mixing in high-temperature implosions; the first direct assessment of the ion-acoustic decay instability in a large-scale length, hot plasma; measurements of polarization mode dispersion and group-velocity walkaway in birefringent media using a frequency domain interferometer; an evaluation of the magnetic flux dynamics occurring in an optically triggered, thin-film superconducting switch; the effect of slurry fluid chemistry on particle size distribution during aqueous polishing of optical glass; and the influence of thermal and mechanical processing history in the preparation of well-ordered liquid crystal elastomer systems.
Date: December 31, 1994
Creator: Marshall, Kenneth L.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 51, April-June 1992 (open access)

LLE Review, Quarterly Report: Volume 51, April-June 1992

This volume of the LLE Review, covering the period April--June 1992, contains articles on laser-plasma interaction experiments in long-scale-length plasmas and on the theory of a new form of the stimulated Brillouin scattering instabilitity. The advanced technology section includes reports on the optical response of superconducting films, the development of high-reflectance transport mirrors for the OMEGA Upgrade, and a new high-brightness mono-mode laser oscillator. Finally, the activities of the National Laser Users Facility and the GDL and OMEGA laser systems are summarized.
Date: December 31, 1992
Creator: Short, R. W.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 48, July-September 1991 (open access)

LLE Review, Quarterly Report: Volume 48, July-September 1991

This volume of the LLE Review, contains articles describing the results of imploding-target burnthrough experiments using smoothing by spectral dispersion (SSD), and a practical nonlocal model for electron transport in laser plasmas. The section on advanced technology includes a report on explosion fraction measurements of water-cooled xenon flashlamps, results on perfluorinated copolymer coatings for high-power laser applications, and a time-resolved study of surface disordering of Pb(110). A brief report reviewing the projects from the high school summer student program is also included. Finally, the activities of the National Laser Users Facility and the GDL and OMEGA laser facilities are summarized.
Date: December 31, 1991
Creator: Jaanimagi, P. A.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 52, July-September 1992 (open access)

LLE Review, Quarterly Report: Volume 52, July-September 1992

This volume of the LLE Review, covering the period July--September 1992, contains articles on methods of balancing the beam power on the OMEGA Upgrade and on the damping of ion-sound waves in laser-produced plasmas. The advanced technology section includes reports on optical nonlinearities in high-temperature superconductors, a method of increasing gas retention time for laser-fusion targets, and a study of stimulated Raman scattering of laser beams in air. Highlights of the research reported in this issue are: An efficient method has been developed for balancing the power in the 60 beams of the OMEGA Upgrade. The method can achieve 2% power balance for both main and foot beams using only four system shots. A study of ion-sound-wave damping has substantially revised and expanded our knowledge of this effect. The damping of ion waves can have important consequences for laser-plasma interaction. The use of femtosecond laser pulses to study the properties of thin-film, high-temperature superconductors is discussed. A method for increasing the gas retention time of polymer-shell laser-fusion targets by overcoating them with a thin layer of aluminum is described. A code has been developed to study stimulated rotational Raman scattering in high-power laser beams propagating through air.
Date: December 31, 1992
Creator: Short, R. W.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 56, July-September 1993 (open access)

LLE Review, Quarterly Report: Volume 56, July-September 1993

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 …
Date: December 31, 1993
Creator: Hutchison, R. J.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 53, October-December 1992 (open access)

LLE Review, Quarterly Report: Volume 53, October-December 1992

This volume of the LLE Review covers the three-month period October--December 1992. On 18 December, the OMEGA Laser Facility fired its last shot. It will be decommissioned during the next quarter to make room for the OMEGA Upgrade Laser Facility. This volume deals with two areas of interest for the OMEGA Upgrade, the development of advanced x-ray and neutron diagnostics and the development of long-pulse (>1-ns) laser sources. The first three articles discuss the development of time-dependent diagnostics. The development of an x-ray framing camera is described and measurements of the high-voltage pulse propagation in the camera are presented. Time-resolved and time-integrated neutron diagnostics for the OMEGA Upgrade are then discussed. Two schemes for the generation of >1-ns laser pulses are presented. Finally, the activities of the National Laser Users Facility and the GDL and OMEGA laser facilities are summarized.
Date: December 31, 1992
Creator: Meyerhofer, D. D.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 57, October-December 1993 (open access)

LLE Review, Quarterly Report: Volume 57, October-December 1993

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.
Date: December 31, 1993
Creator: Simon, A.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 60, July-September 1994 (open access)

LLE Review, Quarterly Report: Volume 60, July-September 1994

This volume contains articles on efficient generation of second-harmonic radiation from short-pulse lasers; calculation of the stabilization cutoff wave numbers for the Rayleigh-Taylor instability; a high-frequency silicon optical modulator; the angular dependence of stimulated Brillouin scattering; and femtosecond dynamics of ladder polymers. Three of these articles--second-harmonic generation, Rayleigh-Taylor cutoff wave numbers, and angular dependence of Brillouin scattering--are directly related to the OMEGA Upgrade, currently under construction. A summary of the status of the OMEGA Upgrade laser facility and the NLUF News for FY94 are included in this volume.
Date: December 31, 1994
Creator: Knauer, J. P.
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 77, October-December 1998 (open access)

LLE Review, Quarterly Report: Volume 77, October-December 1998

This volume of the LLE Review, covering the period October--December 1998, includes two articles addressing issues applicable to direct-drive ICF on the National Ignition Facility (NIF): laser-plasma interactions and laser-irradiation uniformity. Additional highlights of the research presented in this issue are: (1) P.B. Radha and S. Skupsky present a novel charged-particle diagnostic that performs simultaneous {rho}R measurements of the fuel, shell, and ablator regions of a compressed ICF target, consisting of an inner DT fuel region, a plastic (CH) shell, and an ablator (CD), by measuring the knock-on deuteron spectrum. (2) F. Dahmani, S. Burns, J. Lambropoulos, S. Papernov, and A. Schmid report results from stress-inhibited laser-driven crack propagation and stress-delayed damage-initiation experiments in fused silica at 351 nm. Research is underway presently to determine the ramifications of these findings for large-aperture systems, such as OMEGA. (3) V. Goncharov presents an analytic theory of the ablative Richtmyer-Meshkov instability, which shows that the main stabilizing mechanism of the ablation-front perturbations is the dynamic overpressure of the blowoff plasma with respect to the target material. The perturbation evolution during the shock transit time is studied to determine the initial conditions for the Rayleigh-Taylor phase of the instability and to analyze the level …
Date: December 31, 1998
Creator: Regan, S. P.
System: The UNT Digital Library