Search NASA⌕ Search

SEARCH · Search NASA

Results for “Earth's core”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Properties and Acceleration Mechanisms of Electrons Up To 200 keV Associated With a Flux Rope Pair and Reconnection X-Lines Around It in Earth's Plasma Sheet

The properties and acceleration mechanisms of electrons (<200 keV) associated with a pair of tailward traveling flux ropes and accompanied reconnection X-lines in Earth's plasma sheet are investigated with MMS measurements. Energetic electrons are enhanced on both boundaries and core of the flux ropes. The power-law spectra of energetic electrons near the X-lines and in flux ropes are harder than those on flux rope boundaries. Theoretical calculations show that the highest energy of adiabatic electrons is a few keV around the X-lines, tens of keV immediately downstream of the X-lines, hundreds of keV on the flux rope boundaries, and a few MeV in the flux rope cores. The X-lines cause strong energy dissipation, which may generate the energetic electron beams around them. The enhanced electron parallel temperature can be caused by the curvature-driven Fermi acceleration and the parallel electric potential. Betatron acceleration due to the magnetic field compression is strong on flux rope boundaries, which enhances energetic electrons in the perpendicular direction. Electrons can be trapped between the flux rope pair due to mirror force and parallel electric potential. Electrostatic structures in the flux rope cores correspond to potential drops up to half of the electron temperature. The energetic electrons and the electron distribution functions in the flux rope cores are suggested to be transported from other dawn-dusk directions, which is a 3-dimensional effect. The acceleration and deceleration of the Betatron and Fermi processes appear alternately indicating that the magnetic field and plasma are turbulent around the flux ropes.

58 GEOSCIENCES↗
DOE OSTI2020

The Gaia–Kepler Stellar Properties Catalog. II. Planet Radius Demographics as a Function of Stellar Mass and Age

Studies of exoplanet demographics require large samples and precise constraints on exoplanet host stars. Using the homogeneous Kepler stellar properties derived using the Gaia Data Release 2 by Berger et al., we recompute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age. We measure the stellar mass dependence of the planet radius valley to be dlogR{sub p}/dlogM{sub ⋆} = 0.26{sub −0.16}{sup +0.21}, consistent with the slope predicted by a planet mass dependence on stellar mass (0.24–0.35) and core-powered mass loss (0.33). We also find the first evidence of a stellar age dependence of the planet populations straddling the radius valley. Specifically, we determine that the fraction of super-Earths (1–1.8 R{sub ⊕}) to sub-Neptunes (1.8–3.5 R{sub ⊕}) increases from 0.61 ± 0.09 at young ages (<1 Gyr) to 1.00 ± 0.10 at old ages (>1 Gyr), consistent with the prediction by core-powered mass loss that the mechanism shaping the radius valley operates over Gyr timescales. Additionally, we find a tentative decrease in the radii of relatively cool (F {sub p} < 150 F{sub ⊕}) sub-Neptunes over Gyr timescales, which suggests that these planets may possess H/He envelopes instead of higher mean molecular weight atmospheres. We confirm the existence of planets within the hot sub-Neptunian “desert” (2.2 R {sub ⊕} < R {sub p} < 3.8 R{sub ⊕}, F {sub p} > 650 F{sub ⊕}) and show that these planets are preferentially orbiting more evolved stars compared to other planets at similar incident fluxes. In addition, we identify candidates for cool (F {sub p} < 20 F{sub ⊕}) inflated Jupiters, present a revised list of habitable zone candidates, and find that the ages of single and multiple transiting planet systems are statistically indistinguishable.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Wolffia, a minimalist plant and synthetic biology chassis

A highly simplified species for genome engineering would facilitate rational design of a synthetic plant. A candidate species is the aquatic, non-grass monocot wolffia (Wolffia australiana) in the Lemnaceae family. Commonly known as watermeal, wolffia is a rootless ball of several thousand cells the size of a pinhead and the fastest growing plant known on Earth. Its extreme morphological reduction is coupled to transposon-mediated streamlining of its transcriptome, which represents a core set of nonredundant protein coding genes. Despite its body plan and transcriptome being highly specialized for continuous growth, wolffia retains cell types relevant to higher plants. Finally, systems level studies with this species could enable the creation of a defined biological chassis for synthetic plant construction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Thermal conductivity of CaSiO 3 perovskite at lower mantle conditions

Thermal conductivity (κ) of mantle minerals is key to understanding dynamics in the deep Earth. It controls the style of mantle convection and the timescale of cooling both the mantle and the core. Cubic CaSiO 3 perovskite (CaPv) is the third most abundant mineral in the lower mantle (7 vol %). Despite its importance, no theoretical or experimental estimate of CaPv's κ is available. Theoretical investigations of its properties are challenging because of its strong anharmonicity. Experimental measurements at relevant pressures and temperatures are equally challenging. Here we present ab initio results for CaPv's κ obtained using the phonon quasiparticle approach to address its strong anharmonicity. We also offer experimental measurements of κ up to 67 GPa and 1950 K. Predictions and measurements are in good agreement and reveal a surprisingly large κ for cubic CaPv that can be explained on the basis of its high crystal structure symmetry. Despite its relatively low abundance, CaPv's κ increases the lower mantle κ by ~10 %, if accounted for. κ of mantle regions enriched in subducted crustal materials will be more strongly impacted.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Flux Switching Permanent Magnet Motor with Metal Amorphous Nanocomposite Soft Magnetic Material and Rare Earth Free Permanent Magnets

The power losses in high power-density motors due to high rotational speed and/or high pole counts may be reduced adopting metal amorphous nanocomposites (MANCs) featuring low power loss and a relatively high flux density (~1.3 T). We recently proposed a flux switching permanent magnet (FSPM) motor with a rating of 2.5 kW at 1400 Hz electrical speed by incorporating low loss (< 3 W/kg at 1 kHz) FeNi-based MANC material with projected iron loss of about 5 W. The motor design allows use of rare earth-free permanent magnets. For incorporation of MANC materials, an axial flux motor where the rotor and stator core are made from a wound ribbon core has been developed. We have performed a 3-d FEA to optimize the design and built and tested a prototype demonstrating that the low loss MANC material can be used for motor applications.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2022

Radiation-Hardened GaN HEMT and Cell Design, Modeling, and Fabrication for Nuclear Instrumentation Applications

Recent advances in nuclear power generation technologies show great promise for efficient, safe generation of carbon-free power in the near future. Consequently, many new generation reactor designs are being pursued by government and industry groups, including both fission- and fusion-based technologies. Radiation- and temperature-tolerant sensor technology continues to advance, yet development of the electronics/instrumentation technologies suitable for these environments have fallen behind. Industry has adequately addressed harsh environment electronics needs for low earth orbit satellites, but the much more extreme conditions associated with electronics placed near or in a reactor core remain unaddressed. This project investigates the use of gallium nitride (GaN) circuit technology to address the unique needs for sensor interface electronics and communications in reactor environments. This report provides a summary of the first year’s project activities related to developing and optimizing devices and circuits for this GaN high electronic mobility transistor (HEMT) process. Activities reported include multiple analog and digital circuit designs simulated using custom Verilog-A models generated from measured GaN devices fabricated in the target process. Digital circuit designs included fundamental logic circuits such as an inverter, NAND, NOR, AND and OR gates, as well as a 5-stage ring oscillator. Each design was simulated using an open-source SPICE simulator, and an integrated circuit layout was produced of each design for use in future fabrication. Analog circuit designs focused on the fundamental building blocks to be used to construct sensor interface and communications circuits. These included current mirrors, matched differential pairs, and a Gilbert cell mixer design, each with an associated integrated circuit layout. Layout tools used for these designs included two open-source packages—KLayout and Magic—which were customized for specific use with the OSU GaN process layers. Design rules and preliminary device extraction capabilities were built for the Magic tool to enable device extraction and subsequent netlist generation for SPICE simulation. Finally, future research directions for year two are summarized. When the year-two directions are implemented, the project will be in position to advance the state of the art in electronics for near- or in-reactor sensor interfacing and communications.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Board on Earth Sciences and Resources and Its Activities

The National Academies’ Board on Earth Sciences and Resources (BESR) and its standing committees provide an ongoing forum for advancing the understanding and communication of Earth sciences and resource topics, including emerging topics and innovative techniques. BESR activities help to provide evidence-based information to members of the executive and legislative branches of the federal government, the private sector, states and tribes, academia, non-governmental organizations, and the public to support decision-making. BESR and its standing Committee on Solid Earth Geophysics (COSEG), also supported by this award, fulfill this role through development and administration of consensus studies, as well as workshops and other convening activities related to the Earth sciences; overseeing selected activities of the Board’s standing committees, such as disciplinary meetings and webinars; and communicating, sharing information, and providing opportunities for interaction and exchange among technical and non-technical stakeholders. The core support received from DOE helps BESR and COSEG maintain a central body of volunteer experts and National Academies staff who can respond to pressing needs and requests from federal sponsors and other members of the Earth science community, to maintain the health and relevance of the Earth sciences discipline, and to provide the Earth science community with a privileged interface to the government to support scientific and engineering advances and decision making related to Earth sciences and engineering. Initiation and oversight of Earth science activities at the National Academies is an enduring function of the BESR and COSG that helps to ensure development and completion of projects and activities that are responsive to the needs of sponsors and the broader Earth science and research enterprise.

58 GEOSCIENCES↗
DOE OSTI2025

Development of High Energy Resolution Fluorescence Detection Methods for Advanced Microscale X-ray Absorption Fine Structure Analysis of Critical Elements (Final Report)

This project is developing High-Energy Resolution Fluorescence Detection (HERFD) X-ray Absorption Fine-Structure Spectroscopy (XAFS) at the hard X-ray microprobe beamline at GSECARS beamline 13-ID-E, at the Advanced Photon Source at Argonne National Laboratory. This enhancement will improve sensitivity and spectral interpretation limitations of conventional XAFS which uses energy dispersive solid-state detectors (SSD) to measure the total fluorescence yield (TFY-XAFS). By using high-quality Si and Ge crystal analyzers to select X-ray fluorescence (XRF) from specific emission lines, background signals from other elements or X-ray scattering that can paralyze SSDs can be nearly eliminated, improving the sensitivity to the oxidation and chemical state of dilute species even though the solid angle of the analyzers is relatively small. Furthermore, by using analyzers of low-strain Si or Ge, the energy selection can be smaller than the natural widths of the core electron level. We are particularly interested in applying these enhanced sensitivities to Lanthanide series of rare-earth elements, which are typically at concentrations at or below 10 ppm, and where spectral overlaps with the 3rd row transition metals degrade sensitivity.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Chalcogen isotopes reveal limited volatile contribution from late veneer to Earth

The origin of Earth’s volatile elements is highly debated. Comparing the chalcogen isotope ratios in the bulk silicate Earth (BSE) to those of its possible building blocks, chondritic meteorites, allows constraints on the origin of Earth’s volatiles; however, these comparisons are complicated by potential isotopic fractionation during protoplanetary differentiation, which largely remains poorly understood. Using first-principles calculations, we find that core-mantle differentiation does not notably fractionate selenium and tellurium isotopes, while equilibrium evaporation from early planetesimals would enrich selenium and tellurium in heavy isotopes in the BSE. The sulfur, selenium, and tellurium isotopic signatures of the BSE reveal that protoplanetary differentiation plays a key role in establishing most of Earth’s volatile elements, and a late veneer does not substantially contribute to the BSE’s volatile inventory.

58 GEOSCIENCES↗
DOE OSTI2023

Extending Magnetic Core Shell Nanoparticle Extraction Technology to Cesium and Antimony Removal from Geothermal Brines in New Zealand

Our industrial client (Geo40) has developed and deployed a process to remove silica from geothermal fluids and produce a high-margin specialty colloidal silica product comparable to those of market leaders. Geo40 now wishes to explore opportunities to extend their mineral extraction operations to other elements that are present in these brines. Geo40 has identified cesium (Cs) that is present in Ohaaki brines (pH ~8–8.5) at parts per million levels and could be sold to customers if it could be produced at an attractive price. With support from the Department of Energy’s (DOE’s) Geothermal Technologies Office, a simple and highly cost-effective magnetic nanofluid method for extraction of rare earth elements (REEs) from geothermal brine solutions has been developed and demonstrated at the laboratory bench scale at Pacific Northwest National Laboratory (PNNL). Core shell sorbent particles are produced using an iron oxide core particle, which is used to anchor and grow a surrounding adsorbent shell functionalized with a chelating ligand that selectively binds REEs. We extended PNNL’s work by exploring new sorbent shells that are highly selective for Cs. Uptake of Cs was measured as a function of exposure time by analyzing solution samples extracted from batch sorption tests.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Improving Time Step Convergence in an Atmosphere Model With Simplified Physics: The Impacts of Closure Assumption and Process Coupling

Convergence testing is a common practice in the development of dynamical cores of atmospheric models but is not as often exercised for the parameterization of sub-grid physics. An earlier study revealed that the stratiform cloud parameterizations in several predecessors of the Energy Exascale Earth System Model (E3SM) showed strong time-step sensitivity and slower-than-expected convergence when the model's time step was systematically refined. In this work, a simplified atmosphere model is configured that consists of the spectral-element dynamical core of the E3SM atmosphere model coupled with a large-scale condensation parameterization based on commonly used assumptions. This simplified model also resembles E3SM and its predecessors in the numerical implementation of process coupling and shows poor time-step convergence in short ensemble tests. We present a formal error analysis to reveal the expected time-step convergence rate and the conditions for obtaining such convergence. Numerical experiments are conducted to investigate the root causes of convergence problems. We show that revisions in the process coupling and closure assumption help to improve convergence in short simulations using the simplified model; the same revisions applied to a full atmosphere model lead to significant changes in the simulated long-term climate. This work demonstrates that causes of convergence issues in atmospheric simulations can be understood by combining analyses from physical and mathematical perspectives. Addressing convergence issues can help to obtain a discrete model that is more consistent with the intended representation of the physical phenomena.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Sequim Campus Master Plan

Based in Richland, Washington, Pacific Northwest National Laboratory (PNNL) is one of ten U.S. Department of Energy (DOE) Office of Science (SC) national laboratories. PNNL is DOE’s premier chemistry, earth sciences, and data analytics laboratory, delivering vital mission impacts in energy resiliency and national security. PNNL has 19 core capabilities, each a powerful combination of world-class staff, state-of-the- art equipment, and mission-ready facilities. These capabilities represent a collective set of skills and a body of world-leading scientific and engineering work that provides exceptional value and mission delivery to DOE, the National Nuclear Security Administration (NNSA), the U.S. Department of Homeland Security (DHS), and other federal agencies and industry through strategic partnership projects on a not-to-interfere basis. Currently operated by Battelle Memorial Institute, PNNL occupies more than 2.3 million gross square feet (GSF) of buildings and employs approximately 4,700 staff members. PNNL has implemented a rolling 10-year campus strategy, initiated in fiscal year 2013, designed to deliver the foundation for the multidisciplinary science and engineering expertise, equipment, instrumentation, facilities, and infrastructure required to continue providing exceptional value and mission delivery. This strategy is incorporated into PNNL’s annual Laboratory Plan, which serves as DOE-SC’s equivalent of the Five- Year Site Plan required by DOE Order 430.1C Chg. 1, Real Property Asset Management. The PNNL Sequim Campus is located in Clallam County, just outside of Sequim, Washington. PNNL Sequim builds upon a rich history of research related to marine and coastal resources, environmental chemistry, water resources modeling, ecotoxicology, biotechnology, and national security. Facilities at the PNNL Sequim Campus were designed to take advantage of two unique locational assets: the pristine coastal ocean water in Sequim Bay and the region’s exceptionally clean air. Research facilities on the waterfront are supplied with up to 200 gallons per minute (gpm) of seawater and/or groundwater that enables research on aquatic systems ranging from fully seawater to fresh water, with an onsite water treatment system that removes all biological and hazardous chemical residues prior to discharge. Multiple large seawater tanks outside the waterfront laboratories, along with a boat ramp, pier, and floating dock, enable lab-to-field research. The uplands facility takes advantage of the amazing air quality and is built and operated to enable ultratrace chemical/radiological analytical chemistry. This combination of capabilities is not available at any other marine laboratory in the nation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Aspects of rare earth element enrichment in Allegheny Plateau coals, Pennsylvania, USA

The Allegheny Plateau in western Pennsylvania, western Maryland, and northern West Virginia has relatively flat-lying strata with southwest-northeast-trending anticlines cored by splay faults originating from the thrust faults and southeast-northwest-trending lineaments. The lineaments define both the structural relief of the anticlines and the coal rank. Coal rank in the Pennsylvanian Allegheny Group coals is medium volatile bituminous in the region of less-prominent structural relief and low volatile bituminous in the region with more pronounced anticlines. Zinc and Cl exhibit high values in coals in the vicinity of the lineaments. Although coal rank was not a parameter in the Principal components analysis, the highest rank coals clustered together in a quadrant defined, in part, by the Zn concentration. Zinc was selected as a parameter due to its possible link with hydrothermal mineralization and Zr and TiO 2 /Al 2 O 3 were selected based on their presumed association with detrital mineral influences. The highest rare earths + Y values in benches of the Lower Kittanning coal were found at sites close to the lineaments. Negative or negligible Ce anomalies (δCe) and strongly positive Gd anomalies (δGd) suggest marine or hydrothermal influences and negative Eu anomalies (δEu) along with high TiO 2 /Al 2 O 3 values suggest a terrestrial input. In conclusion, the plots of δCe vs. δGd and δCe vs. δEu show that the low volatile bituminous coals are segregated from the other coals, suggesting that the factors that influenced coal rank also influenced the distribution of the rare earth elements.

58 GEOSCIENCES↗
DOE OSTI2024

Global Ocean Cooling of 2.3°C During the Last Glacial Maximum

Abstract Quantitative constraints on past mean ocean temperature (MOT) critically inform our historical understanding of Earth's energy balance. A recently developed MOT proxy based on paleoatmospheric Xe, Kr, and N 2 ratios in ice core air bubbles is a promising tool rooted in the temperature dependences of gas solubilities. However, these inert gases are systematically undersaturated in the modern ocean interior, and it remains unclear how air‐sea disequilibrium may have changed in the past. Here, we carry out 30 tracer‐enabled model simulations under varying circulation, sea ice cover, and wind stress regimes to evaluate air‐sea disequilibrium in the Last Glacial Maximum (LGM) ocean. We find that undersaturation of all three gases was likely reduced, primarily due to strengthened high‐latitude winds, biasing reconstructed MOT by −0.38 ± 0.37°C (1σ). Accounting for air‐sea disequilibrium, paleoatmospheric inert gases indicate that LGM MOT was 2.27 ± 0.46°C (1σ) colder than the pre‐industrial era.

Seltzer, A. M.↗
DOE OSTI2025

Thermoelastic Properties of Iron-Rich Ringwoodite and the Deep Mantle Aerotherm of Mars

The Martian mantle is considered to have a higher Fe/Mg ratio than the Earth's mantle. Ringwoodite, γ-(Mg,Fe) 2 SiO 4 , is likely the dominant polymorph of olivine in the core-mantle boundary (CMB) region of Mars. We synthesized anhydrous iron-rich ringwoodite with molar Mg/(Mg + Fe) = 0.44 and determined its thermal equation of state up to 35 GPa and 750 K by synchrotron X-ray diffraction. Using a third order Birch-Murnaghan equation of state, we obtain K T0 = 182 (3) GPa, K' = 4.6 (2), and α 0 = 3.18 (6) × 10 -5 K -1 . Using these results and an updated mineralogical model with an iron-rich composition of Mg/(Mg + Fe) = 0.75 for the Martian mantle, we estimate ~1900 K for the temperature of the D1000 seismic discontinuity inside Mars. The resulting adiabat predicts a warm aerotherm, which could explain the presence of partial melt at the CMB of Mars recently detected with seismic data from the 2019 InSight mission.

58 GEOSCIENCES↗
DOE OSTI2021

A clustering-based approach to ocean model–data comparison around Antarctica

The Antarctic Continental Shelf seas (ACSS) are a critical, rapidly changing element of the Earth system. Analyses of global-scale general circulation model (GCM) simulations, including those available through the Coupled Model Intercomparison Project, Phase 6 (CMIP6), can help reveal the origins of observed changes and predict the future evolution of the ACSS. However, an evaluation of ACSS hydrography in GCMs is vital: previous CMIP ensembles exhibit substantial mean-state biases (reflecting, for example, misplaced water masses) with a wide inter-model spread. Because the ACSS are also a sparely sampled region, grid-point-based model assessments are of limited value. Our goal is to demonstrate the utility of clustering tools for identifying hydrographic regimes that are common to different source fields (model or data), while allowing for biases in other metrics (e.g., water mass core properties) and shifts in region boundaries. We apply K-means clustering to hydrographic metrics based on the stratification from one GCM (Community Earth System Model version 2; CESM2) and one observation-based product (World Ocean Atlas 2018; WOA), focusing on the Amundsen, Bellingshausen and Ross seas. When applied to WOA temperature and salinity profiles, clustering identifies “primary” and “mixed” regimes that have physically interpretable bases. For example, meltwater-freshened coastal currents in the Amundsen Sea and a region of high-salinity shelf water formation in the southwestern Ross Sea emerge naturally from the algorithm. Both regions also exhibit clearly differentiated inner- and outer-shelf regimes. The same analysis applied to CESM2 demonstrates that, although mean-state model biases in water mass T–S characteristics can be substantial, using a clustering approach highlights that the relative differences between regimes and the locations where each regime dominates are well represented in the model. CESM2 is generally fresher and warmer than WOA and has a limited fresh-water-enriched coastal regimes. Given the sparsity of observations of the ACSS, this technique is a promising tool for the evaluation of a larger model ensemble (e.g., CMIP6) on a circum-Antarctic basis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Perovskite Catalysts for Pure-Water-Fed Anion-Exchange-Membrane Electrolyzer Anodes: Co-design of Electrically Conductive Nanoparticle Cores and Active Surfaces

Anion-exchange-membrane water electrolyzers (AEMWEs) are a possible low-capital-expense, efficient, and scalable hydrogen-production technology with inexpensive hardware, earth-abundant catalysts, and pure water. However, pure-water-fed AEMWEs remain at an early stage of development and suffer from inferior performance compared with proton-exchange-membrane water electrolyzers (PEMWEs). One challenge is to develop effective non-platinum-group-metal (non-PGM) anode catalysts and electrodes in pure-water-fed AEMWEs. We show how LaNiO3-based perovskite oxides can be tuned by cosubstitution on both A- and B-sites to simultaneously maintain high metallic electrical conductivity along with a degree of surface reconstruction to expose a stable Co-based active catalyst. The optimized perovskite, Sr0.1La0.9Co0.5Ni0.5O3, yielded pure-water AEMWEs operating at 1.97 V at 2.0 A cm-2 at 70 °C with a pure-water feed, thus illustrating the utility of the catalyst design principles.

Zhai, Tingting↗