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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Study of Nonlinear Evolution of the Weibel-like Instability of Relativistic Electron Beams Relevant to Fast Ignition and Astrophysics

Relativistic laser matter interaction generates an intense fast electron beam with Mega ampere (MA) to Giga-ampere current. Such beam can propagate into high-density plasmas as background plasma electrons can provide sufficient return current to maintain charge and current neutrality. However, such system is subject to Weibel-like filamentation instabilities that break out the beam into filaments and generate intense magnetic fields. This could result in anomalous stopping and large angular spread of the electron beams, leading to a lower energy coupling to the fuel in the fast ignition (FI) scheme of inertial confinement fusion, therefore, of significant interest to FI. Understanding the nonlinear growth of the Weibel B-fields and its structure is also important to astrophysics as it is generally accepted to be responsible for relativistic collisionless shocks and cosmic rays and “jitter” radiation in gamma ray burst.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Review of Recent Literature Relevant to the Environmental Effects of Marine and Hydrokinetic Energy Devices; Task 2.1.3: Effects on Aquatic Organisms - Fiscal Year 2012 Progress Report

A literature search was conducted by using the Web of Science® databases component of the ISI Web of Knowledge to identify recent articles that would be useful to help assess the potential environmental effects of renewable energy development in the ocean, with emphasis on seabirds and fish. Several relatively recent general review articles that included possible effects on seabirds and fish were examined to begin the search process. From these articles, several general topics of potential environmental effects on seabirds and fish were derived. These topics were used as the primary search factors. Additional sources were identified by cross-checking the Web of Science databases for articles that cited the review articles.

Green Sturgeon↗
DOE OSTI2013

LWRS Program - Updates of High-Fluence Induced Microstructural Evolution of Austenitic Stainless Steels under LWR Relevant Conditions

Components serving in a nuclear reactor plant must withstand a very harsh environment including extended time at temperature, neutron irradiation, stress, and/or corrosive media. The many modes of degradation are complex and vary depending on location and material. However, understanding and managing materials degradation is a key for the continued safe and reliable operation of nuclear power plants

Busby, Jeremy T.↗
DOE OSTI2013

Coupled Euler-Lagrange Simulation of the Jolt HE Event and Relevance to the Shock Physics Experiments

The goal of the Shock Physics Experiments is to increase our understanding of the shock phenomenology from an explosive event to aid in modeling these events. A more accurate understanding of the effects of near source geology on that phenomenology is critical. We demonstrated the use of the multi physics Abaqus ® fully coupled Euler-Lagrange code to model the DTRA JOLT experiment. Abaqus/CEL was able to compute the high-deformation explosive loading, the complex rock response with damage, and the large general contact domain. Comparison of results to test data reveals that the simulation performed credibly. These results provide insight into propagati0n of explosive-caused shock in jointed media. This exercise provides evidence that the shock front is not perturbed by the joints. While it is possible that later time, lower amplitude portions of the waveform can exhibit behavior caused by joints, we conclude that the main shock events from the SPE events is not effected by the local jointing.

58 GEOSCIENCES↗
DOE OSTI2013

Interface Induced Carbonate Mineralization: A Fundamental Geochemical Process Relevant to Carbon Sequestration

We have approached the long-standing geochemical question why anhydrous high-Mg carbonate minerals (i.e., magnesite and dolomite) cannot be formed at ambient conditions from a new perspective by exploring the formation of MgCO 3 and Mg x Ca{sub (1-x)}CO 3 in non-aqueous solutions. Data collected from our experiments in this funding period suggest that a fundamental barrier, other than cation hydration, exists that prevents Mg 2+ and CO 3 2- ions from forming long-range ordered structures. We propose that this barrier mainly stems from the lattice limitation on the spatial configuration of CO 3 groups in magnesite crystals. On the other hand, the measured higher distribution coefficients of Mg between magnesian calcites formed in the absence and presence of water give us a first direct proof to support and quantify the cation hydration effect.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Rheology Of MonoSodium Titanate (MST) And Modified Mst (mMST) Mixtures Relevant To The Salt Waste Processing Facility

The Savannah River National Laboratory performed measurements of the rheology of suspensions and settled layers of treated material applicable to the Savannah River Site Salt Waste Processing Facility. Suspended solids mixtures included monosodium titanate (MST) or modified MST (mMST) at various solid concentrations and soluble ion concentrations with and without the inclusion of kaolin clay or simulated sludge. Layers of settled solids were MST/sludge or mMST/sludge mixtures, either with or without sorbed strontium, over a range of initial solids concentrations, soluble ion concentrations, and settling times.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Interface Induced Carbonate Mineralization: A Fundamental Geochemical Process Relevant to Carbon Sequestration

Carbonate mineralization and polymorphic formation are key issues in underground CO 2 storage and biomineralization processes and closely related to mineral substrates. We investigated effects of mineral surfaces, solution chemistry, and anhydrous organic solvent on nucleation and growth of Ca-Mg-carbonate minerals. The effect of substrates of mica, diopside, tremolite, and hematite on calcite nucleation and growth in both experimental and natural environments were investigated using SEM, XRD, and EBSD methods. EBSD analysis can determine orientations between substrates and calcite crystals effectively.

58 GEOSCIENCES↗
DOE OSTI2013

Surface-supported Ag islands stabilized by a quantum size effect: Their interaction with small molecules relevant to ethylene epoxidation

This dissertation focuses on how QSE-stabilized, surface-supported Ag nanoclusters will interact with ethylene or oxygen. Experiments are performed to determine whether the QSE-mediated Ag islands react differently toward adsorption of ethylene or oxygen, or whether the adsorption of these small molecules will affect the QSE-mediated stability of Ag islands. Studies of the interaction of oxygen with Ag/Si(111)-7×7 were previously reported, but these studies were performed at a low Ag coverage where 3D Ag islands were not formed. So the study of such a system at a higher Ag coverage will be a subject of this work. The interaction of ethylene with Ag/Si(111)-7×7, as well as the interaction of oxygen with Ag/NiAl(110) are also important parts of this study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Theoretical and experimental studies of electrified interfaces relevant to energy storage

Advances in technology for electrochemical energy storage require increased understanding of electrolyte/electrode interfaces, including the electric double layer structure, and processes involved in charging of the interface, and the incorporation of this understanding into quantitative models. Simplified models such as Helmholtz's electric double-layer (EDL) concept don't account for the molecular nature of ion distributions, solvents, and electrode surfaces and therefore cannot be used in predictive, high-fidelity simulations for device design. This report presents theoretical results from models that explicitly include the molecular nature of the electrical double layer and predict critical electrochemical quantities such as interfacial capacitance. It also describes development of experimental tools for probing molecular properties of electrochemical interfaces through optical spectroscopy. These optical experimental methods are designed to test our new theoretical models that provide descriptions of the electric double layer in unprecedented detail.

25 ENERGY STORAGE↗
DOE OSTI2014

Ultrafast Structural Dynamics in Combustion Relevant Model Systems

The research project explored the time resolved structural dynamics of important model reaction system using an array of novel methods that were developed specifically for this purpose. They include time resolved electron diffraction, time resolved relativistic electron diffraction, and time resolved Rydberg fingerprint spectroscopy. Toward the end of the funding period, we also developed time-resolved x-ray diffraction, which uses ultrafast x-ray pulses at LCLS. Those experiments are just now blossoming, as the funding period expired. In the following, the time resolved Rydberg Fingerprint Spectroscopy is discussed in some detail, as it has been a very productive method. The binding energy of an electron in a Rydberg state, that is, the energy difference between the Rydberg level and the ground state of the molecular ion, has been found to be a uniquely powerful tool to characterize the molecular structure. To rationalize the structure sensitivity we invoke a picture from electron diffraction: when it passes the molecular ion core, the Rydberg electron experiences a phase shift compared to an electron in a hydrogen atom. This phase shift requires an adjustment of the binding energy of the electron, which is measurable. As in electron diffraction, the phase shift depends on the molecular, geometrical structure, so that a measurement of the electron binding energy can be interpreted as a measurement of the molecule’s structure.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2014

Prioritization Study of Elements Relevant to RIMS Counter-WMD

A systematic study of the priority in which elements should be investigated in order to maximize the possible impact on RIMS Counter-WMD research has been carried out. Candidate elements included U, Th, transuranic elements, and select fission products such as Tc and Eu. This list has been updated to reflect assessments based on potential utility to debris diagnostics as well as the degree of complexity required to develop the RIMS method for the measurement of expected isotope abundances. Factors considered in this study include production of actinides in a fission environment, the existence of available resonance ionization-specific spectroscopic work, as well as practical experimental considerations (sample synthesis for research and activity/safety considerations). The resultant prioritized list of additional elements (beyond U) to be carried forward in this study are, in order of interest, Pu, Am, and Np. If resources and time lines permit, we would also like to investigate Th and Eu. Cm would be a final choice due to the logistics of creating and handling higher activity, short-lived materials, and the paucity of pre-existing spectroscopic studies.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Multi-dimensional collective effects in high-current relativistic beams relevant to High Density Laboratory Plasmas

In summary, an analytical model describing the self-pinching of a relativistic charge-neutralized electron beam undergoing the collisionless Weibel instability in an overdense plasma has been developed. The model accurately predicts the final temperature and size of the self-focused filament. It is found that the final temperature is primarily defined by the total beam’s current, while the filament’s radius is shown to be smaller than the collisionless skin depth in the plasma and primarily determined by the beam’s initial size. The model also accurately predicts the repartitioning ratio of the initial energy of the beam’s forward motion into the magnetic field energy and the kinetic energy of the surrounding plasma. The density profile of the final filament is shown to be a superposition of the standard Bennett pinch profile and a wide halo surrounding the pinch, which contains a significant fraction of the beam’s electrons. PIC simulations confirm the key assumption of the analytic theory: the collisionless merger of multiple current filaments in the course of the Weibel Instability provides the mechanism for Maxwellization of the beam’s distribution function. Deviations from the Maxwell-Boltzmann distribution are explained by incomplete thermalization of the deeply trapped and halo electrons. It is conjectured that the simple expression derived here can be used for understanding collsionless shock acceleration and magnetic field amplification in astrophysical plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2014

Seismic and hydroacoustic analysis relevant to MH370

The vicinity of the Indian Ocean is searched for open and readily available seismic and/or hydroacoustic stations that might have recorded a possible impact of MH370 with the ocean surface. Only three stations are identified: the IMS hydrophone arrays H01 and H08, and the Geoscope seismic station AIS. Analysis of the data from these stations shows an interesting arrival on H01 that has some interference from an Antarctic ice event, large amplitude repeating signals at H08 that obscure any possible arrivals, and large amplitude chaotic noise at AIS precludes any analysis at higher frequencies of interest. The results are therefore rather inconclusive but may point to a more southerly impact location within the overall Indian Ocean search region. The results would be more useful if they can be combined with any other data that are not readily available.

58 GEOSCIENCES↗
DOE OSTI2014

Investigation of Dynamic Aerodynamics and Control of Wind Turbine Sections Under Relevant Inflow/Blade Attitude Conditions

The growth of wind turbines has led to highly variable loading on the blades. Coupled with the relative reduced stiffness of longer blades, the need to control loading on the blades has become important. One method of controlling loads and maximizing energy extraction is local control of the flow on the wind turbine blades. The goal of the present work was to better understand the sources of the unsteady loading and then to control them. This is accomplished through an experimental effort to characterize the unsteadiness and the effect of a Gurney flap on the flow, as well as an analytical effort to develop control approaches. It was planned to combine these two efforts to demonstrate control of a wind tunnel test model, but that final piece still remains to be accomplished.

17 WIND ENERGY↗
DOE OSTI2014

Framework for Probabilistic Projections of Energy-Relevant Streamflow Indicators under Climate Change Scenarios for the U.S.

This project focuses on uncertainty in streamflow forecasting under climate change conditions. The objective is to develop easy to use methodologies that can be applied across a range of river basins to estimate changes in water availability for realistic projections of climate change. There are three major components to the project: Empirical downscaling of regional climate change projections from a range of Global Climate Models; Developing a methodology to use present day information on the climate controls on the parameterizations in streamflow models to adjust the parameterizations under future climate conditions (a trading-space-for-time approach); and Demonstrating a bottom-up approach to establishing streamflow vulnerabilities to climate change. The results reinforce the need for downscaling of climate data for regional applications, and further demonstrates the challenges of using raw GCM data to make local projections. In addition, it reinforces the need to make projections across a range of global climate models. The project demonstrates the potential for improving streamflow forecasts by using model parameters that are adjusted for future climate conditions, but suggests that even with improved streamflow models and reduced climate uncertainty through the use of downscaled data, there is still large uncertainty is the streamflow projections. The most useful output from the project is the bottom-up vulnerability driven approach to examining possible climate and land use change impacts on streamflow. Here, we demonstrate an inexpensive and easy to apply methodology that uses Classification and Regression Trees (CART) to define the climate and environmental parameters space that can produce vulnerabilities in the system, and then feeds in the downscaled projections to determine the probability top transitioning to a vulnerable sate. Vulnerabilities, in this case, are defined by the end user.

54 ENVIRONMENTAL SCIENCES↗