LLE Review, Quarterly Report: Volume 54, January-March 1993 (open access)

LLE Review, Quarterly Report: Volume 54, January-March 1993

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.
Date: July 1, 1993
Creator: Meyerhofer, D. D.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 114, January-March 2008 (open access)

LLE Review, Quarterly Report: Volume 114, January-March 2008

This volume of the LLE Review, covering January-March 2008, features 'Cryogenic Targets: Current Status and Future Development', by D. R. Harding, D. H. Edgell, M. D. Wittman, L. M. Elasky, S. J. Verbridge, A. J. Weaver, L. D. Lund, W. Seka, W. T. Shmayda, R. T. Janezic, M. J. Shoup III, M. Moore, R. Junquist, and A. V. Okishev. In this article (p. 57), the authors report on the status of layering cryogenic DT and D{sub 2} targets at LLE for inertial confinement fusion (ICF) targets. This critical effort achieves the important milestone of routinely providing cryogenic DT targets that meet the 1.0-{micro}m (rms) OMEGA ice-quality-surface specification. The best D{sub 2}-ice layers produced so far (rms roughness of 1.1 {micro}m) are approaching the quality typically achieved in DT targets. Efforts to improve the consistency of this process are reported along with investigations supporting the National Ignition Campaign studying issues relevant to indirect-drive and direct-drive cryogenic targets. Additional highlights of recent research presented in this issue include the following: (1) an improved laser speckle smoothing scheme that augments the current NIF 1-D SSD system by using multiple-FM modulators (MultiFM 1-D SSD) (p. 73). With a judicious choice of modulator frequencies, MultiFM …
Date: July 30, 2008
Creator: Zuegel, Jonathan D.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 58, January-March 1994 (open access)

LLE Review, Quarterly Report: Volume 58, January-March 1994

This volume of the LLE Review, covering the period Jan - Mar 1994, contains articles on backlighting diagnostics; the effect of electron collisions on ion-acoustic waves and heat flow; using PIC code simulations for analysis of ultrashort laser pulses interacting with solid targets; creating a new instrument for characterizing thick cryogenic layers; and a description of a large-aperture ring amplifier for laser-fusion drivers. Three of these articles - backlighting diagnostics; characterizing thick cryogenic layers; and large-aperture ring amplifier - are directly related to the OMEGA Upgrade, now under construction. Separate abstracts have been prepared for articles from this report.
Date: July 1, 1994
Creator: Simon, A.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 62, January-March 1995 (open access)

LLE Review, Quarterly Report: Volume 62, January-March 1995

This volume of the LLE review, covering the period of January-March 1995, contains articles on the evaluation of the mechanism for laser damage in OMEGA UV multilayer coatings using a combination of conventional laser-damage characterization methods and atomic force microscopy; a dual-amplitude, fiber-coupled waveguide integrated-optic modulation device for generating temporally shaped optical pulses in OMEGA-, a proposal for modifying the indirect-drive irradiation geometry of the National Ignition Facility (NIF) to provide the additional flexibility for performing direct-drive experiments; direct measurements of terminal-level lifetime in several different Nd:YLF laser media; an overview of the materials science issues, basic mechanisms, and potential device applications for light-emitting porous silicon; and a study of the time-dependent reflection and surface temperatures for laser-irradiated dental hard tissue at two CO{sub 2} laser wavelengths.
Date: July 1, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 68, July-September 1996 (open access)

LLE Review, Quarterly Report: Volume 68, July-September 1996

This volume of the LLE Review, covering the period of July-September 1996, includes a description of an important experiment carried out on OMEGA by researchers from LANL, LLNL, and LLE to demonstrate the feasibility of using OMEGA for indirect drive. Additional topics include tetrahedral hohlraums, the speckle properties of phase- converted laser beams, design criteria for SSD phase modulators, and the design of slab amplifiers. Highlights of the research presented in this issue are (1) Results from the proof-of-principle indirect- drive experiments in which up to 40 OMEGA beams were used to irradiate cylindrical hohlraums. Nova results were reproduced, and new capabilities not available on other lasers were demonstrated. (2) A discussion of tetrahedral hohlraums (spherical hohlraums with four laser entrance holes) as a means of achieving better capsule irradiation uniformity. Tetrahedral hohlraums also allow the use of all 60 OMEGA beams and may provide an alternate route to ignition on the NIF. (3) An analysis of the residual target irradiation nonuniformity due to the fine laser speckle remaining on the beam after being phase converted by the DPP`s. A model shows how a uniformly ablating plasma atmosphere reduces the speckle contribution to the effective time-averaged irradiation nonuniformity. (4) A …
Date: July 1, 1996
Creator: Skledon, Mark E.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 74, January-March 1998 (open access)

LLE Review, Quarterly Report: Volume 74, January-March 1998

This volume of the LLE Review covers the period January--March 1998. The first of eight articles documents the in-house development, scale-up, and manufacture of 60 continuous distributed phase plates with high laser-damage resistance. D.J. Smith et al. describe how inert ion beams were used to etch a continuously varying pattern into the surface of fused silica to form these devices. Other highlights of research presented in this issue are: (1) a soft x-ray microscope with high spatial resolution has been characterized and used for initial experiments on the OMEGA laser system, F.J. Marshall et al. give details of the testing, calibration, and initial use of this microscope for studying the hydrodynamic stability of directly driven planar foils; (2) D.K. Bradley et al. report on a series of experiments designed to investigate hydrodynamic instability growth in direct-drive capsule implosions; (3) C.J. McKinstrie et al. report on the use of systematic perturbation methods to derive formulas for the Landau damping rates of electron-plasma and ion-acoustic waves; (4) high efficiency and good beam quality are potential advantages of the end-pumped solid-state lasers over the side-pumped ones, A. Babushkin et al. describe their successful use of a transport fiber to end-pump a Nd:YLF laser, …
Date: July 1, 1998
Creator: Jacobs, S. D.
Object Type: Report
System: The UNT Digital Library