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At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Ag BL Description for General Atomics

The Material Strength campaign at LLNL is an effort to measure the resistance of materials to deformation when placed under large stresses. These experiments are carried out at large laser facilities, where a laser-driven plasma pusher creates a pressure in excess of 5 Mbar (on the NIF) or 1 Mbar (at OMEGA) in the sample of interest. Strong materials resist deforming in response to these high pressures, and the magnitude of the strength can be inferred using an x-ray probe traversing the sample. The x-ray source used for this probe must be bright, high-energy, and spatially coherent. To achieve all of these things, silver micro-wires and micro-flags are an essential diagnostic tool.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Performance Characteristics of HYDRA - a Multi-Physics simulation code from Lawrence Livermore National Laboratory

HYDRA is used to simulate a variety of experiments carried out at the National Ignition Facility (NIF) [4] and other high energy density physics facilities. HYDRA has packages to simulate radiation transfer, atomic physics, hydrodynamics, laser propagation, and a number of other physics effects. HYDRA has over one million lines of code and includes both MPI and thread-level (OpenMP and pthreads) parallelism. This paper measures the performance characteristics of HYDRA using hardware counters on an IBM BlueGene/Q system. We report key ratios such as bytes/instruction and memory bandwidth for several different physics packages. The total number of bytes read and written per time step is also reported. We show that none of the packages which use significant time are memory bandwidth limited on a Blue Gene/Q. HYDRA currently issues very few SIMD instructions. The pressure on memory bandwidth will increase if high levels of SIMD instructions can be achieved.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Material for Point Design (final summary of DIME material)

These slides summarize the motivation of the Defect Induced Mix Experiment (DIME) project, the “point design” of the Polar Direct Drive (PDD) version of the NIF separated reactant capsule, the experimental requirements, technical achievements, and some useful backup material. These slides are intended to provide much basic material in one convenient location and will hopefully be of some use for subsequent experimental projects.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

PRP Review of shots beyond FY14 Q1/Q2 Report

On February 4, 2013 the Peer Review Panel, as part of the NIF Governance plan, met along with the HED and ICF councils, to review 7 campaigns that were additional to (or expanded from) those considered since the June 2013 PRP review of the proposed shots that had been planned for Q1 and Q2 of FY14 (and beyond). We summarize here our findings, followed by a paragraph of details on each of the 7 campaigns we reviewed.

42 ENGINEERING↗
DOE OSTI2014

Los Alamos National Laboratory Inertial Confinement fusion (ICF) Highlights, May 2014

• 25 shots on Omega measured the effect of initial surface roughness on the evolution of mixing due to shear flow. • First experiments on Omega EP of the oblique shock experiment returned high-quality radiographs showing instability growth. • Completed design of first beryllium-capsule laser pulse for NIF that will assess risk of SBS backscatter.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Laser Safety Gram 0035 Advanced Radiographic Capabilities

This revision covers the addition of a short pulse alignment laser to the ARC Diagnostic Table (ADT). The Advanced Radiographic Capabilities (ARC) is a diagnostic that can redirect up to four NIF beam lines (Q35T) through two compressor vessels, splitting each beam line into two beamlets, and generating up to eight distinct pulses with a pulse-width on the order of 10s of picoseconds (figure 1). The up to eight generated pulses will be staggered to backlighter targets in order to create an x-ray movie of the compression phase leading up to ignition and other purposes.

42 ENGINEERING↗
DOE OSTI2014

Summary of May 21st and 22nd Shear Campaign [Slides]

We have streaked imaging of both smooth and roughened foils in both Ti and Al at both early and late times. Further work will be needed to check if the signal is strong enough on all shots to extract reliable mix-widths. The initial test of the 3 slit streaked imaging setup was unsuccessful. Streaked images of a driven shots using the slit on the target resulted in low signal, while un-driven shots showed much higher signals. The working hypothesis is that the signal dropped due to slit closure on the target; the successful NIF setup used a much wider slit, on the order of 100 um instead of 20 um. We were able to get good streak data by switching back to a 20 um pinhole at the front of the SSCA and removing the slits from the targets. To obtain the best late-time streak data we had to overlap the two TIM4 BL groups (on the BL driver). We have sets of plan view radiographs for at least three different times for both smooth and roughened foils in both Ti and Al. There are visually identifiable difference between the plan view radiographs of the smooth and enhanced roughened foils. The enhanced roughening is apparent in the plan view images at early times and seems to persist as the dominant structure scale into late times. We have several streaked plan view images. Further analysis will be required to determine if this can be turned into a viable platform for turbulence studies. Signal strength on the Al streaked plan view looks promising.

Plasma Physics & Fusion Technology(70)↗
DOE OSTI2014

Ab Initio Nuclear Structure and Reaction Calculations for Rare Isotopes

We have developed a novel ab initio symmetry-adapted no-core shell model (SA-NCSM), which has opened the intermediate-mass region for ab initio investigations, thereby providing an opportunity for first-principle symmetry-guided applications to nuclear structure and reactions for nuclear isotopes from the lightest p-shell systems to intermediate-mass nuclei. This includes short-lived proton-rich nuclei on the path of X-ray burst nucleosynthesis and rare neutron-rich isotopes to be produced by the Facility for Rare Isotope Beams (FRIB). We have provided ab initio descriptions of high accuracy for low-lying (including collectivity-driven) states of isotopes of Li, He, Be, C, O, Ne, Mg, Al, and Si, and studied related strong- and weak-interaction driven reactions that are important, in astrophysics, for further understanding stellar evolution, X-ray bursts and triggering of s, p, and rp processes, and in applied physics, for electron and neutrino-nucleus scattering experiments as well as for fusion ignition at the National Ignition Facility (NIF).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Research Performance Progress Report

The major goals of this project is to develop a suite of diagnostics to probe magnetic fields generated by the dynamics of high velocity interpenetrating plasma flows relevant to astrophysical collisionless shocks. Collisionless shocks are common in the universe and are responsible for decelerating and thermalizing supersonic plasma flows and accelerating a fraction of the incident particles to high energies. When high velocity, low density, plasma flows interact in astrophysics, turbulent electrostatic and electromagnetic waves are generated due to plasma instabilities, such as the Weibel instability. This can lead to localized pockets of very strong magnetic field generation. The net result is that the plasmas stagnate in what is called a collisionless shock. Understanding these enigmatic interactions requires well-controlled laboratory experiments able to validate the theory and the simulations. Time and spatially resolved magnetic field diagnostics are key to probing these frontier plasma dynamics, relevant to both astrophysics and laboratory applications of plasma physics. This project will enable us to develop the necessary diagnostics for this experiment on NIF. Our team has vast experience in performing laser experiments, theory, simulations and diagnostic development and is ideally suited for carrying out this work.

42 ENGINEERING↗
DOE OSTI2014

Simulation Study of Near-Surface Coupling of Nuclear Devices vs. Equivalent High-Explosive Charges

A computational study was performed to examine the differences in near-surface ground-waves and air-blast waves generated by high-explosive energy sources and those generated by much higher energy - density low - yield nuclear sources. The study examined the effect of explosive-source emplacement (i.e., height-of-burst, HOB, or depth-of-burial, DOB) over a range from depths of -35m to heights of 20m, for explosions with an explosive yield of 1-kt . The chemical explosive was modeled by a JWL equation-of-state model for a ~14m diameter sphere of ANFO (~1,200,000kg – 1 k t equivalent yield ), and the high-energy-density source was modeled as a one tonne (1000 kg) plasma of ‘Iron-gas’ (utilizing LLNL’s tabular equation-of-state database, LEOS) in a 2m diameter sphere, with a total internal-energy content equivalent to 1 k t . A consistent equivalent-yield coupling-factor approach was developed to compare the behavior of the two sources. The results indicate that the equivalent-yield coupling-factor for air-blasts from 1 k t ANFO explosions varies monotonically and continuously from a nearly perfec t reflected wave off of the ground surface for a HOB ≈ 20m, to a coupling factor of nearly zero at DOB ≈ -25m. The nuclear air - blast coupling curve, on the other hand, remained nearly equal to a perfectly reflected wave all the way down to HOB’s very near zero, and then quickly dropped to a value near zero for explosions with a DOB ≈ -10m. The near - surface ground - wave traveling horizontally out from the explosive source region to distances of 100’s of meters exhibited equivalent - yield coupling - factors t hat varied nearly linearly with HOB/DOB for the simulated ANFO explosive source, going from a value near zero at HOB ≈ 5m to nearly one at DOB ≈ -25m. The nuclear-source generated near-surface ground wave coupling-factor remained near zero for almost all HOB’s greater than zero, and then appeared to vary nearly - linearly with depth-of-burial until it reached a value of one at a DOB between 15m and 20m. These simulations confirm the expected result that the variation of coupling to the ground, or the air, change s much more rapidly with emplacement location for a high-energy-density (i.e., nuclear-like) explosive source than it does for relatively low - energy - density chemical explosive sources. The Energy Partitioning, Energy Coupling (EPEC) platform at LLNL utilizes laser energy from one quad (i.e. 4-laser beams) of the 192 - beam NIF Laser bank to deliver ~10kJ of energy to 1mg of silver in a hohlraum creating an effective small-explosive ‘source’ with an energy density comparable to those in low-yield nuclear devices. Such experiments have the potential to provide direct experimental confirmation of the simulation results obtained in this study, at a physical scale (and time-scale) which is a factor of 1000 smaller than the spatial- or temporal-scales typically encountered when dealing with nuclear explosions.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2014

National Ignition Facility Target Diagnostic Waveform Digitization

The purpose of this document is to assess various technologies in electrical waveform digitization for applications at the National Ignition Facility (NIF), more specifically, the Target Diagnostic (TD) department. The findings and recommendations in this memo are meant to inform decisions for future diagnostic implementations and to guide plans for upgrades to existing systems that, due to age or inherent deficiencies, require renewal.

42 ENGINEERING↗
DOE OSTI2015

Response to FESAC survey, Non-Fusion Connections to Fusion Energy Sciences. Long Duration Directional Drives for Star Formation and Photoionization

Due to the iconic status of the pillars of the Eagle Nebula, this research will bring popular attention to plasma physics, HED laboratory physics, and fundamental science at NIF and other experimental facilities. The result will be to both to bring new perspectives to the studies of hydrodynamics in inertial confinement fusion and HED scenarios in general, and to promote interest in the STEM disciplines.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Long Duration Directional Drives for Star Formation and Photoionization

This research will; confirm the possibility of studying the structure and evolution of star-forming regions of molecular clouds in the laboratory; test the cometary model for the formation of the pillar structures in molecular clouds; assess the effect of magnetic fields on the evolution of structures in molecular clouds; and develop and demonstrate a new, long-duration (60-100 ns), directional source of x-ray radiation that can be used for the study of deeply nonlinear hydrodynamics, hydrodynamic instabilities that occur in the presence of directional radiation, shock-driven and radiatively-driven collapse of dense cores, and photoionization. Due to the iconic status of the pillars of the Eagle Nebula, this research will bring popular attention to plasma physics, HED laboratory physics, and fundamental science at NIF and other experimental facilities. The result will be to both to bring new perspectives to the studies of hydrodynamics in inertial confinement fusion and HED scenarios in general, and to promote interest in the STEM disciplines.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Studies of HED Plasmas with Self-Generated Magnetic Field

High-amplitude sub-Larmor-scale electromagnetic turbulence is ubiquitous in high-energy density environments, such as laboratory plasmas produced by high-intensity lasers, e.g., NIF, Omega-EP, Trident, and others, and in astrophysical and space plasmas, e.g., at high-Mach-number collisionless shocks in weakly magnetized plasmas upstream regions of quasi-parallel shocks, sites of magnetic reconnection and others. Studies of plasmas and turbulence in these environments are important for fusion energy sciences and the inertial confinement concept, in particular, as well as to numerous astrophysical systems such as gamma-ray bursts, supernovae blast waves, jets of quasars and active galactic nuclei, shocks in the interplanetary medium, solar flares and many more. Such turbulence can be of various origin and thus have rather different properties, from being purely magnetic (Weibel) turbulence to various types of electromagnetic turbulence (for example, whistler wave turbulence or turbulence produced by filamentation or Weibel-type streaming instability), to purely electrostatic Langmuir turbulence. In this project we use analytical and numerical tools to study the transport, radiative, and magneto-optical properties of plasmas with sub-Larmor-scale turbulence. We discovered the connection of transport/diffusion properties to certain spectral benchmark features of (jitter) radiation produced by the plasma and radiation propagation through it. All regimes, from the relativistic to non-relativistic, were thoroughly investigated and predictions were made for laboratory plasmas and astrophysical plasmas. Thus, all the tasks outlined in the proposal were fully and successfully accomplished.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

New Routes for the Production of Fission Products and Their Separation from the Source Material for the Development of Realistic Nuclear Forensic Debris

In order to fully characterize the NIF neutron spectrum, SAND-II-SNL software was requested/received from the Radiation Safety Information Computational Center. The software is designed to determine the neutron energy spectrum through analysis of experimental activation data. However, given that the source code was developed in Sparcstation 10, it is not compatible with current version of FORTRAN. Accounts have been established through the Lawrence Livermore National Laboratory’s High Performance Computing in order to access different compiles for FORTRAN (e.g. pgf77, pgf90). Additionally, several of the subroutines included in the SAND-II-SNL package have required debugging efforts to allow for proper compiling of the code.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Status of Indirect Drive ICF Experiments on the National Ignition Facility

In the quest to demonstrate Inertial Confinement Fusion (ICF) ignition of deuterium-tritium (DT) filled capsules and propagating thermonuclear burn with net energy gain (fusion energy/laser energy >1), recent experiments on the National Ignition Facility (NIF) have shown progress towards increasing capsule hot spot temperature (Tion>5 keV) and fusion neutron yield (~10 16 ), while achieving ~2x yield amplification by alpha particle deposition. At the same time a performance cliff was reached, resulting in lower fusion yields than expected as the implosion velocity was increased. Ongoing studies of the hohlraum and capsule physics are attempting to disseminate possible causes for this performance ceiling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Update of Earthquake Strong-Motion Instrumentation at Lawrence Livermore National Laboratory

Following the January 1980 earthquake that was felt at Lawrence Livermore National Laboratory (LLNL), a network of strong-motion accelerographs was installed at LLNL. Prior to the 1980 earthquake, there were no accelerographs installed. The ground motion from the 1980 earthquake was estimated from USGS instruments around the Laboratory to be between 0.2 – 0.3 g horizontal peak ground acceleration. These instruments were located at the Veterans Hospital, 5 miles southwest of LLNL, and in San Ramon, about 12 miles west of LLNL. In 2011, the Department of Energy (DOE) requested to know the status of our seismic instruments. We conducted a survey of our instrumentation systems and responded to DOE in a letter. During this survey, it was found that the recorders in Buildings 111 and 332 were not operational. The instruments on Nova had been removed, and only three of the 10 NIF instruments installed in 2005 were operational (two were damaged and five had been removed from operation at the request of the program). After the survey, it was clear that the site seismic instrumentation had degraded substantially and would benefit from an overhaul and more attention to ongoing maintenance. LLNL management decided to update the LLNL seismic instrumentation system. The updated system is documented in this report.

42 ENGINEERING↗