Instability growth seeded by oxygen in CH shells on the National Ignition Facility
Not Available
Haan, S. W.↗
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Three-dimensional simulations of National Ignition Facility implosions: Insight into experimental observables
We simulate in 3D both the hydrodynamics and, simultaneously, the X-ray and neutron diagnostic signatures of National Ignition Facility (NIF) implosions. We apply asymmetric radiation drive to study the impact of low mode asymmetry on diagnostic observables. We examine X-ray and neutron images as well as neutron spectra for these perturbed implosions. The X-ray images show hot spot evolution on small length scales and short time scales, reflecting the incomplete stagnation seen in the simulation. The neutron images show surprising differences from the X-ray images. The neutron spectra provide additional measures of implosion asymmetry. Flow in the hot spot alters the neutron spectral peak, namely, the peak location and width. The changes in the width lead to a variation in the apparent temperature with viewing angle that signals underlying hot spot asymmetry. We compare our new expectations based on the simulated data with NIF data. We find that some recent cryogenic layered experiments show appreciable temperature anisotropy indicating residual flow in the hot spot. We also find some trends in the data that do not reflect our simulation and theoretical understanding.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Simulation study of 3–5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser
Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3–5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (∼n{sub c}/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from CRETIN, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3–5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ∼100–150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (∼20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3–5 keV x-ray source on NIF.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Hydrodynamic instability growth of three-dimensional, “native-roughness” modulations in x-ray driven, spherical implosions at the National Ignition Facility
Hydrodynamic instability growth experiments with three-dimensional (3-D) surface-roughness modulations were performed on plastic (CH) shell spherical implosions at the National Ignition Facility (NIF) [E. M. Campbell, R. Cauble, and B. A. Remington, AIP Conf. Proc. 429, 3 (1998)]. The initial capsule outer-surface roughness was similar to the standard specifications (“native roughness”) used in a majority of implosions on NIF. The experiments included instability growth measurements of the perturbations seeded by the thin membranes (or tents) used to hold the capsules inside the hohlraums. In addition, initial modulations included two divots used as spatial fiducials to determine the convergence in the experiments and to check the accuracy of 3D simulations in calculating growth of known initial perturbations. The instability growth measurements were performed using x-ray, through-foil radiography of one side of the imploding shell, based on time-resolved pinhole imaging. Averaging over 30 similar images significantly increases the signal-to-noise ratio, making possible a comparison with 3-D simulations. At a convergence ratio of ∼3, the measured tent and divot modulations were close to those predicted by 3-D simulations (within ∼15%–20%), while measured 3-D, broadband modulations were ∼3–4 times larger than those simulated based on the growth of the known imposed initial surface modulations. In addition, some of the measured 3-D features in x-ray radiographs did not resemble those characterized on the outer capsule surface before the experiments. One of the hypotheses to explain the results is based on the increased instability amplitudes due to modulations of the oxygen content in the bulk of the capsule. As the target assembly and handling procedures involve exposure to UV light, this can increase the uptake of the oxygen into the capsule, with irregularities in the oxygen seeding hydrodynamic instabilities. These new experimental results have prompted looking for ways to reduce UV light exposure during target fabrication.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Note: A monoenergetic proton backlighter for the National Ignition Facility
A monoenergetic, isotropic proton source suitable for proton radiography applications has been demonstrated at the National Ignition Facility (NIF). A deuterium and helium-3 gas-filled glass capsule was imploded with 39 kJ of laser energy from 24 of NIF’s 192 beams. Spectral, spatial, and temporal measurements of the 15-MeV proton product of the {sup 3}He(d,p){sup 4}He nuclear reaction reveal a bright (10{sup 10} protons/sphere), monoenergetic (ΔE/E = 4%) spectrum with a compact size (80 μm) and isotropic emission (∼13% proton fluence variation and <0.4% mean energy variation). Simultaneous measurements of products produced by the D(d,p)T and D(d,n){sup 3}He reactions also show 2 × 10{sup 10} isotropically distributed 3-MeV protons.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility
Not Available
Schneider, M. B.↗
Capsule implosions for continuum x-ray backlighting of opacity samples at the National Ignition Facility
Direct drive implosions of plastic capsules have been performed at the National Ignition Facility to provide a broad-spectrum (500–2000 eV) X-ray continuum source for X-ray transmission spectroscopy. The source was developed for the high-temperature plasma opacity experimental platform. Initial experiments using 2.0 mm diameter polyalpha-methyl styrene capsules with ~20 μm thickness have been performed. X-ray yields of up to ~1 kJ/sr have been measured using the Dante multichannel diode array. The backlighter source size was measured to be ~100 μm FWHM, with ~350 ps pulse duration during the peak emission stage. Lastly, these results are used to simulate transmission spectra for a hypothetical iron opacity sample at 150 eV, enabling the derivation of photometrics requirements for future opacity experiments.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Three-wavelength scheme to optimize hohlraum coupling on the National Ignition Facility
Not Available
Michel, P.↗
Managing EHS of PV-Related Equipment at the National Renewable Energy Laboratory: Preprint
Managing environment, health, and safety (EHS) risks at a national laboratory, or university, can be intimidating to a researcher who is focused on research results. Laboratory research and development (R&D) operations are often driven by scientists with limited engineering support and lack well-refined equipment development resources. To add to the burden for a researcher, there is a plethora ofcodes, standards, and regulations that govern the safe installation and operation of photovoltaic-related R&D equipment -- especially those involving hazardous production materials. To help guide the researcher through the vast list of requirements, the EHS office at NREL has taken a variety of steps. Organizationally, the office has developed hazard-specific laboratory-level procedures togovern particular activities. These procedures are a distillation of appropriate international codes, fire agencies, SEMI standards, U.S. Department of Energy orders, and other industry standards to those necessary and sufficient to govern the safe operation of a given activity. The EHS office works proactively with researchers after a concept for a new R&D capability is conceived to help guidethe safe design, acquisition, installation, and operation of the equipment. It starts with a safety assessment at the early stages such that requirements are implemented to determine the level of risk and degree of complexity presented by the activity so appropriate controls can be put in place to manage the risk. As the equipment requirements and design are refined, appropriate equipmentstandards are applied. Before the 'to-build' specifications are finalized, a process hazard analysis is performed to ensure that no single-point failure presents an unacceptable risk. Finally, as the tool goes through construction and installation stages, reviews are performed at logical times to ensure that the requisite engineering controls and design are in place and operational.Authorization to operate is not given until adherence to these requirements is fully verified and documented. Operations continue under the conditions defined through this process and are reviewed with changing processes.
14 SOLAR ENERGY↗
Idaho National Laboratory Ten-Year Site Plan Project Description Document: Descriptions of the capital projects delineated in the Idaho National Laboratory 2013 - 2022 Ten-Year Site Plan as of June 2011
This document describes the currently active and proposed infrastructure projects listed in Appendix B of the Idaho National Laboratory 2013-2022 Ten Year Site Plan (DOE/ID-11449). It was produced in accordance with Contract Data Requirements List I.06. The projects delineated in this document support infrastructure needs at INL's Research and Education Campus, Materials and Fuels Complex, Advanced Test Reactor Complex and the greater site-wide area. The projects provide critical infrastructure needed to meet current and future INL operational and research needs. Execution of these projects will restore, rebuild, and revitalize INL's physical infrastructure; enhance program execution, and make a significant contribution toward reducing complex-wide deferred maintenance.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
AVTA Federal Fleet PEV Readiness Data Logging and Characterization Study for the National Park Service: Fort Vancouver National Historic Site
Battelle Energy Alliance, LLC, managing and operating contractor for the U.S. Department of Energy’s Idaho National Laboratory, is the lead laboratory for the U.S. Department of Energy’s Advanced Vehicle Testing. Battelle Energy Alliance, LLC contracted with Intertek Testing Services, North America (ITSNA) to collect data on federal fleet operations as part of the Advanced Vehicle Testing Activity’s Federal Fleet Vehicle Data Logging and Characterization study. The Advanced Vehicle Testing Activity study seeks to collect data to validate the use of advanced electric drive vehicle transportation.
33 ADVANCED PROPULSION SYSTEMS↗
The Power of Invention: National Security Science and Beyond at Los Alamos National Laboratory
According to Webster, a genius is someone who possesses uncommon powers of intellect, particularly the power of invention. Those who call Los Alamos National Laboratory their professional home have a tremendous power of invention — their genius benefits from atomic power. Nuclear weapons are the heart of the Laboratory’s origin story. It is why we are here. They are also central to the multiple innovations inspired and driven by such atomic work — in ways that might surprise you. Our search for solutions outside the realm of nuclear security is nevertheless built on the incredible innovations and challenges driven by a defining moment in our world’s history — the advent of the nuclear weapon.
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
Wind Integration National Dataset (WIND) Toolkit; NREL (National Renewable Energy Laboratory)
A webinar about the Wind Integration National Dataset (WIND) Toolkit was presented by Bri-Mathias Hodge and Caroline Draxl on July 14, 2015. It was hosted by the Southern Alliance for Clean Energy. The toolkit is a grid integration data set that contains meteorological and power data at a 5-minute resolution across the continental United States for 7 years and hourly power forecasts.
17 WIND ENERGY↗
Creating the National Renewable Energy Laboratory: Implications for New National Energy Research Institutes
The history of the design and development of the National Renewable Energy Laboratory (NREL) in the United States illustrates how the plans for a new institute can be realized and evolve over four decades. This history summarizes the process of planning and developing NREL as a new research institute to meet its mandated mission, including creating a research agenda and plans for R&D management, human resources, financial sustainability, and facilities. The NREL origin story, informed by the development of similar institutions around the world, also reveals generalized principles useful for decision makers across the globe who are designing their own research institute. These principles are described in this publication.
energy institute↗
Thermodesulfobacterium geofontis sp. nov., a hyperthermophilic, sulfate-reducing bacterium isolated from Obsidian Pool, Yellowstone National Park
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Stefan, Schouten↗
Integrity of the National Resident Matching Program for Radiation Oncology: National Survey of Applicant Experiences
Purpose: The aim of this study was to examine the experiences of radiation oncology applicants and to evaluate the prevalence of behaviors that may be in conflict with established ethical standards. Methods and Materials: An anonymous survey was sent to all 2013 applicants to a single domestic radiation oncology residency program through the National Resident Matching Program (NRMP). Questions included demographics, survey of observed behaviors, and opinions regarding the interview and matching process. Descriptive statistics were presented. Characteristics and experiences of respondents who matched were compared with those who did not match. Results: Questionnaires were returned by 87 of 171 applicants for a 51% response rate. Eighty-two questionnaires were complete and included for analysis. Seventy-eight respondents (95.1%) reported being asked at least 1 question in conflict with the NRMP code of conduct. When asked where else they were interviewing, 64% stated that this query made them uncomfortable. Forty-five respondents (54.9%) reported unsolicited post-interview contact by programs, and 31 (37.8%) felt pressured to give assurances. Fifteen respondents (18.3%) reported being told their rank position or that they were “ranked to match” prior to Match day, with 27% of those individuals indicating this information influenced how they ranked programs. Half of respondents felt applicants often made dishonest or misleading assurances, one-third reported that they believed their desired match outcome could be improved by deliberately misleading programs, and more than two-thirds felt their rank position could be improved by having faculty from their home institutions directly contact programs on their behalf. Conclusions: Radiation oncology applicants report a high prevalence of behaviors in conflict with written NRMP policies. Post-interview communication should be discouraged in order to enhance fairness and support the professional development of future radiation oncologists.
62 RADIOLOGY AND NUCLEAR MEDICINE↗