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Laser coupling to reduced-scale targets at NIF Early Light

Description: Deposition of maximum laser energy into a small, high-Z enclosure in a short laser pulse creates a hot environment. Such targets were recently included in an experimental campaign using the first four of the 192 beams of the National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technology 26, 755 (1994)], under construction at the University of California Lawrence Livermore National Laboratory. These targets demonstrate good laser coupling, reaching a radiation temp… more
Date: August 31, 2005
Creator: Hinkel, D. E.; Schneider, M. B.; Young, B. K.; Holder, J. P.; Langdon, A. B.; Baldis, H. A. et al.
Partner: UNT Libraries Government Documents Department
open access

Parallel graph reduction on a supercomputer: A status report

Description: We describe an ongoing effort to develop a parallel graph reduction run-time system hosted on a multiprocessor supercomputer. This run-time system is presently augmented by the functional language compiler of the ALFALFA system. Admittedly, parallel graph reduction is hardly a novel idea. The interesting notion is the provision of a parallel execution environment sufficiently powerful to support development of large prototypical scientific and symbolic codes in a functional language. This will … more
Date: January 1, 1986
Creator: Michelsen, R.; Smith, L.; Williams, E. & Yantis, B.
Partner: UNT Libraries Government Documents Department
open access

Pixe Analysis of Metals in Sludge and Marine Sediments in the New York Bight Apex. [Analysis of Cr, Mn, Ti, v, and Zn by Proton-Induced X-Ray Emission (Pixe)]

Description: PIXE analysis of acid extracts of marine muds from the N.Y. Bight apex was performed to obtain metal ratios for determining whether the origin was: (a) estuarine outflow, (b) dredge spoil, (c) sewage sludge, or (d) acid waste. Consideration of the ratios: Ti/Zn, Zn/Mn, and V/Cr, for example, lead to certain conclusions which are presented.
Date: January 1, 1977
Creator: Harris, W. H.; Bauman, S. E.; Williams, E. T.; Finston, H. L.; Bond, A. H., Jr. & Lesser, P. M. S.
Partner: UNT Libraries Government Documents Department
open access

A Reduced Model of Kinetic Effects Related to the Saturation of Stimulated Brillouin Scattering

Description: We developed a reduced description of kinetic effects that is included in a fluid model of stimulated Brillouin backscattering (SBS) in low Z plasmas (e.g. He, Be). Following hybrid-PIC simulations, the modified ion distribution function is parametrized by the width {delta} of the plateau created by trapping around the phase velocity of the SBS-driven acoustic wave. An evolution equation is derived for {delta}, which affects SBS through a frequency shift and a reduced Landau damping. This model… more
Date: August 26, 2003
Creator: Divol, L.; Williams, E. A.; Cohen, B. I.; Langdon, A. B. & Lasinski, B. F.
Partner: UNT Libraries Government Documents Department
open access

Analysis of the National Ignition Facility Ignition Hohlraum Energetics Experiments

Description: A series of forty experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] to study energy balance and implosion symmetry in reduced- and full-scale ignition hohlraums was shot at energies up to 1.3 MJ. This paper reports the findings of the analysis of the ensemble of experimental data obtained that has produced an improved model for simulating ignition hohlraums. Last year the first observation in a NIF hohlraum of energy transfer between cones… more
Date: November 22, 2010
Creator: Town, R. J.; Rosen, M. D.; Michel, P. A.; Divol, L.; Moody, J. D.; Kyrala, G. A. et al.
Partner: UNT Libraries Government Documents Department
open access

Estimation of (n,f) Cross-Sections by Measuring Reaction Probability Ratios

Description: Neutron-induced reaction cross-sections on unstable nuclei are inherently difficult to measure due to target activity and the low intensity of neutron beams. In an alternative approach, named the 'surrogate' technique, one measures the decay probability of the same compound nucleus produced using a stable beam on a stable target to estimate the neutron-induced reaction cross-section. As an extension of the surrogate method, in this paper they introduce a new technique of measuring the fission p… more
Date: April 21, 2005
Creator: Plettner, C.; Ai, H.; Beausang, C. W.; Bernstein, L. A.; Ahle, L.; Amro, H. et al.
Partner: UNT Libraries Government Documents Department
open access

The First Experiments on the National Ignition Facility

Description: A first set of laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and x-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in fl… more
Date: November 11, 2005
Creator: Landen, O. L.; Glenzer, S.; Froula, D.; Dewald, E.; Suter, L. J.; Schneider, M. et al.
Partner: UNT Libraries Government Documents Department
open access

New Results on Fission Cross Sections in Actinide Nuclei using the Surrogate Ratio Method and on Conversion Coefficients in Triaxial Strongly Deformed Bands in 167Lu from ICE Ball and Gammasphere

Description: The surrogate ratio technique is described. New results for neutron induced fission cross sections on actinide nuclei, obtained using this technique are presented. The results benchmark the surrogate ratio technique and indicate that the method is accurate to within 5% over a wide energy range. New results for internal conversion coefficients in triaxial strongly deformed bands in {sup 167}Lu are also presented.
Date: January 30, 2007
Creator: Beausang, C. W.; Lesher, S. R.; Burke, J. T.; Bernstein, L. A.; Phair, L.; Ai, H. et al.
Partner: UNT Libraries Government Documents Department
open access

Role of Hydrodynamics Simulations in Laser-Plasma Interaction Predictive Capability

Description: Efforts to predict and control laser-plasma interactions (LPI) in ignition hohlraum targets for the National Ignition Facility [G. H. Miller et al., Optical Eng. 43, 2841 (2004)] are based on plasma conditions provided by radiation hydrodynamic simulations. Recent experiments provide compelling evidence that codes such as hydra [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] can accurately predict the plasma conditions in laser heated targets such as gas-filled balloon (gasbag) and hohlrau… more
Date: November 2, 2006
Creator: Meezan, N. B.; Berger, R. L.; Divol, L.; Froula, D. H.; Hinkel, D. E.; Jones, O. S. et al.
Partner: UNT Libraries Government Documents Department
open access

Kinetic Enhancement of Raman Backscatter, and Electron Acoustic Thomson Scatter

Description: 1-D Eulerian Vlasov-Maxwell simulations are presented which show kinetic enhancement of stimulated Raman backscatter (SRBS) due to electron trapping in regimes of heavy linear Landau damping. The conventional Raman Langmuir wave is transformed into a set of beam acoustic modes [L. Yin et al., Phys. Rev. E 73, 025401 (2006)]. For the first time, a low phase velocity electron acoustic wave (EAW) is seen developing from the self-consistent Raman physics. Backscatter of the pump laser off the EAW f… more
Date: September 1, 2006
Creator: Strozzi, D. J.; Williams, E. A.; Langdon, A. B. & Bers, A.
Partner: UNT Libraries Government Documents Department
open access

Effects of Ion-Ion Collisions and Inhomogeneity in Two-Dimensional Kinetic Ion Simulations of Stimulated Brillouin Backscattering

Description: Two-dimensional simulations with the BZOHAR [B.I. Cohen, B.F. Lasinski, A.B. Langdon, and E.A. Williams, Phys. Plasmas 4, 956 (1997)] hybrid code (kinetic particle ions and Boltzmann fluid electrons) have been used to investigate the saturation of stimulated Brillouin backscatter (SBBS) instability including the effects of ion-ion collisions and inhomogeneity. Ion-ion collisions tend to increase ion-wave dissipation, which decreases the gain exponent for stimulated Brillouin backscattering; and… more
Date: October 17, 2005
Creator: Cohen, B. I.; Divol, L.; Langdon, A. B. & Williams, E. A.
Partner: UNT Libraries Government Documents Department
open access

Successful Completion of the Top-off Upgrade of the Advanced Light Source

Description: An upgrade of the Advanced Light Source to enable top-off operation has been completed during the last four years. The final work centered around radiation safety aspects, culminating in a systematic proof that top-off operation is equally safe as decaying beam operation. Commissioning and transition to full user operations happened in late 2008 and early 2009. Top-off operation at the ALS provides a very large increase in time-averaged brightness (by about a factor of 10) as well as improvemen… more
Date: January 31, 2010
Creator: Steier, C.; Bailey, B.; Baptiste, K.; Barry, W.; Biocca, A.; Byrne, W. et al.
Partner: UNT Libraries Government Documents Department
open access

Modeling the Backscatter and Transmitted Light of High Power Smoothed Beams with pF3D, a Massively Parallel Laser Plasma Interaction Code

Description: Using the three-dimensional wave propagation code, F3D[Berger et al., Phys. Fluids B 5,2243 (1993), Berger et al., Phys. Plasmas 5,4337(1998)], and the massively parallel version pF3D, [Still et al. Phys. Plasmas 7 (2000)], we have computed the transmitted and reflected light for laser and plasma conditions in experiments that simulated ignition hohlraum conditions. The frequency spectrum and the wavenumber spectrum of the transmitted light are calculated and used to identify the relative contr… more
Date: June 1, 2000
Creator: Berger, R. L.; Divol, L.; Glenzer, S.; Hinkel, D. E.; Kirkwood, R. K.; Langdon, A. B. et al.
Partner: UNT Libraries Government Documents Department
open access

Strain and Texture in Al-Interconnect Wires Measured by X-Ray Microbeam Diffraction

Description: The local strain and texture in Al interconnect wires have been investigated using white and monochromatic x-ray microbeams on the MHATTCAT undulator beam line at the Advanced Photon Source. Intergrain and intragrain orientations were obtained with ~0.01 degree sensitivity using white beam measurements on wide Al pads (~100 Mu-m) and thin (2 Mu-m) Al wires. Orientation changes of up to 1 degree were found within individual grains of the (111) textured Al interconnects. Deviatoric strain measure… more
Date: April 5, 1999
Creator: Budai, J. D.; Chung, J.-S.; Ice, G. E.; Larson, B. C.; Lowe, W. P.; Tamura, N. et al.
Partner: UNT Libraries Government Documents Department
open access

Recent laser-plasma interaction studies at LLNL

Description: Recent analysis and modeling of Nova experiments which address our understanding of stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) will be presented. Forward and backward SBS levels have been investigated with SSD of varying bandwidth and with polarization smoothing using an f/8 focusing geometry to emulate NIF conditions. The interpretation of the experiments is aided using F3D, a fluid code which includes modeling of SBS and SRS; a parallel version of F3D is being… more
Date: September 1, 1999
Creator: Berger, R. L.; Decker, C.; Divol, L.; Geddes, C.; Glenzer, S. H.; Hinkel, D. E. et al.
Partner: UNT Libraries Government Documents Department
open access

Effect of queueing disciplines on response times in distributed systems

Description: A distributed program consists of processes, many of which can execute concurrently on different processors in a distributed system of processors. When several processes from the same or different distributed programs have been assigned to a processor in a distributed system, the processor must select the next process to run. The question investigated is: What is an appropriate method for selecting the next process to run. Standard processor queueing disciplines, such as first-come-first-serve … more
Date: January 1, 1984
Creator: Williams, E.
Partner: UNT Libraries Government Documents Department
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