LLE Review, Quarterly Report: Volume 72, July-September 1997 (open access)

LLE Review, Quarterly Report: Volume 72, July-September 1997

This volume of the LLE Review, covering the period July--September 1997, begins with a general introduction to LLE`s experimental physics program and a report on recent results. This article includes a useful summary of the system`s operational capabilities and system parameters. Other highlights of the wide variety of research presented in this issue are: a promising method to directly observe the cold compressed shell of an imploding target. The shell is normally observed by backlighting. The proposal described here is to use a high-Z dopant that fluoresces under radiation from the hot core in the K{alpha} line. A study of the instabilities associated with near-forward stimulated Brillouin scattering. It includes a calculation of the saturation times and steady-state gain exponents. A successful program of pulse shaping for the OMEGA laser system. Examples of a variety of pulse shapes that can be programmed are presented. A description of the angular-scattering characteristics of ferroelectric liquid crystal electro-optical devices operating in transient and extended scattering modes. The possibility of applying these devices as modulators in practical IR imaging systems is evaluated. A faster method of shaping and finishing IR materials by the use of magnetorheological fluids. Detailed specifications and test results are included. …
Date: February 1, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
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 67, April-June 1996 (open access)

LLE Review, Quarterly Report: Volume 67, April-June 1996

This volume contains articles detailing several nonlinear processes associated with lasers and their use, as well as an article describing the computer control systems necessary to maintain and operate a large laser system such as the 60-beam OMEGA laser. The specific topics discussed in this issue include stimulated scattering in laser plasmas, power exchange between interacting laser beams, charged particles interacting with a laser pulse, thermal equilibration of optically excited states, an overview of the laser control system software in OMEGA, and a technique for cancellation of the nonlinear phase accumulation in short-pulse lasers.
Date: November 1, 1996
Creator: Skeldon, Mark D.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 116, July-September 2008 (open access)

LLE Review, Quarterly Report: Volume 116, July-September 2008

This issue has the following articles: (1) Optimizing Electron-Positron Pair Production on kJ-Class High-Intensity Lasers for the Purpose of Pair-Plasma Creation; (2) Neutron Yield Study of Direct-Drive, Low-Adiabat Cryogenic D2 Implosions on OMEGA; (3) Al 1s-2p Absorption Spectroscopy of Shock-Wave Heating and Compression in Laser-Driven Planar Foil; (4) A Measurable Lawson Criterion and Hydro-Equivalent Curves for Inertial Confinement Fusion; (5) Pulsed-THz Characterization of Hg-Based, High-Temperature Superconductors; (6) LLE's Summer High School Research Program; (7) FY08 Laser Facility Report; and (8) National Laser Users Facility and External Users Programs.
Date: March 12, 2010
Creator: Marozas, John A.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 120, July-September 2009 (open access)

LLE Review, Quarterly Report: Volume 120, July-September 2009

This issue has the following articles: (1) The Omega Laser Facility Users Group Workshop; (2) The Effect of Condensates and Inner Coatings on the Performance of Vacuum Hohlraum Targets; (3) Zirconia-Coated-Carbonyl-Iron-Particle-Based Magnetorheological Fluid for Polishing Optical Glasses and Ceramics; (4) All-Fiber Optical Magnetic Field Sensor Based on Faraday Rotation in Highly Terbium Doped Fiber; (5) Femtosecond Optical Pump-Probe Characterization of High-Pressure-Grown Al{sub 0.86}Ga{sub 0.14}N Single Crystals; (6) LLE's Summer High School Research Program; (7) Laser Facility Report; and (8) National Laser Users Facility and External Users Programs.
Date: February 19, 2001
Creator: Edgell, Dana H.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 117, October-December 2008 (open access)

LLE Review, Quarterly Report: Volume 117, October-December 2008

This volume of the LLE Review, covering October-December 2008, features 'Demonstration of the Shock-Timing Technique for Ignition Targets at the National Ignition Facility' by T. R. Boehly, V. N. Goncharov, S. X. Hu, J. A. Marozas, T. C. Sangster, D. D. Meyerhofer (LLE), D. Munro, P. M. Celliers, D. G. Hicks, G. W. Collins, H. F. Robey, O. L. Landen (LLNL), and R. E. Olson (SNL). In this article (p. 1) the authors report on a technique to measure the velocity and timing of shock waves in a capsule contained within hohlraum targets. This technique is critical for optimizing the drive profiles for high-performance inertial-confinement-fusion capsules, which are compressed by multiple precisely timed shock waves. The shock-timing technique was demonstrated on OMEGA using surrogate hohlraum targets heated to 180 eV and fitted with a re-entrant cone and quartz window to facilitate velocity measurements using velocity interferometry. Cryogenic experiments using targets filled with liquid deuterium further demonstrated the entire timing technique in a hohlraum environment. Direct-drive cryogenic targets with multiple spherical shocks were also used to validate this technique, including convergence effects at relevant pressures (velocities) and sizes. These results provide confidence that shock velocity and timing can be measured in …
Date: May 28, 2009
Creator: Bittle, Wade A.
Object Type: Text
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 84, July-September 2000 (open access)

LLE Review, Quarterly Report: Volume 84, July-September 2000

This volume of the LLE Review, covering July-September 2000, begins with an article by T. R. Boehly, V. N. Goncharov, O. Gotchev, J. P. Knauer, D. D. Meyerhofer, D. Oron, S. P. Regan, Y. Srebro, W. Seka, D. Shvarts, S. Skupsky, and V.A. Smalyuk, who describe measurements of the effect of beam smoothing and pulse shape on imprinting. (Imprinting is defined as the imposition of pressure perturbations on the target by spatial variations in the laser intensity.) A principal result is the observation of reduced levels of imprint with the higher beam smoothing afforded by 1-THz smoothing by spectral dispersion (SSD). Additional highlights of research presented in this issue are: (1) P. W. McKenty, V. N. Goncharov, R. P. J. Town, S. Skupsky, R. Betti, and R. L. McCrory describe calculations of directly driven ignition capsule performance on the National Ignition Facility (NIF). The authors detail how the various contributors to implosion disruption (laser imprint, power imbalance, and target roughness) affect target performance and final gain. The conclusions are obtained by examining the simulated target evolution with the two-dimensional hydrodynamics computer code ORCHID. (2) D. D. Meyerhofer, J. A. Delettrez, R. Epstein, V. Yu. Glebov, V. N. Goncharov, R. L. …
Date: December 1, 2000
Creator: Marshall, Frederic J.
Object Type: Report
System: The UNT Digital Library
LLE Review, Quarterly Report: Volume 79, April-June 1999 (open access)

LLE Review, Quarterly Report: Volume 79, April-June 1999

This volume of the Laboratory for Laser Energetics (LLE) Review, covering the period April-June 1999, features a theoretical analysis of direct-drive target performance on National Ignition Facility (NIF). In this article R. P. J. Town, J. A. Delettrez, R. Epstein, V. N. Goncharov, R. L. McCrory, P. W. McKenty, R. W. Short, and S. Skupsky detail ignition target designs developed at LLE specifically to achieve successful direct-drive ignition on the NIF facility. A baseline ''all-DT'' target design is described along with a two shock compression analysis, which includes discussion of the parameters leading to variability in shock timing. The modeling and analysis presented flow down to specification requirements for the laser and target parameters to ignite this baseline target design with the NIF laser.
Date: April 1, 1999
Creator: Morse, Samuel F. B.
Object Type: Report
System: The UNT Digital Library
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.
Object Type: Report
System: The UNT Digital Library