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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 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Large-scale offshore wind farm effects on weather and climate in Puerto Rico (Final Technical Report)

Puerto Rico’s current electricity generation heavily relies on imported fossil fuels. This results in an average cost of electricity higher than the U.S. mainland average in all sectors (residential, commercial, and industrial), despite abundant local offshore wind resources, which have the potential to provide secure, low-cost energy generation and consequent economic prosperity. However, effects on atmospheric and oceanic circulation resulting from large-scale deployments of offshore wind farms have not been previously studied at tropical latitude. This project addressed this knowledge gap through a computational modeling effort designed to capture the coupled dynamics of the atmosphere and the ocean in presence of offshore wind farms. Results indicate that wind farm wakes can alter wind stress, generate Ekman-driven vertical transport, and potentially affect nutrient distribution. While full model coupling remains challenging, progress in parameterization and large-eddy simulations provides a foundation for future research. The project contributes to DOE’s Earth System modeling efforts and supports STEM workforce development.

17 WIND ENERGY↗
DOE OSTI2025

Advancing Neutrino Simulation Modeling with MARLEY: Insights from the NNSA-MSIIP Internship

Core-collapse supernovae are intense sources of tens-of-MeV neutrinos. However, there is no experimental data to validate the current event generator MARLEY (Model of Argon Reaction Low Energy Yields) that can model supernova neutrinos. To validate the model, I developed a new muon capture feature within the MARLEY simulation framework by coding key functions in C++, Python, and ROOT. I generated and analyzed one million simulated muon capture events and comparing the results to experimental data. To improve the model, I worked on optimizing the model’s parameters to improve its precision using statistical methods.

Wong, Baker [Fermilab]↗
DOE OSTI2026

Ultrafast Light-Induced Magnetoelectric Effect in van der Waals Magnetic Semiconductor Heterostructures

Atomic-scale heterostructures of van der Waals (vdW) magnets and semiconductors provide a unique environment for exploring magnetic dynamics. In contrast to typical photothermal excitation of precessional magnetization dynamics by a pump laser pulse, we find that ultrafast optical excitation of a WS2/CrGeTe3 (CGT) bilayer produces an opposite sign of magnetic torque compared to an isolated CGT film. Experimental observations by time-resolved magneto-optic Kerr effect (TR-MOKE) and theoretical analysis by density functional theory (DFT) and Landau-Lifshitz-Gilbert (LLG) simulations support a mechanism in which charge transfer of photoexcited carriers across the interface alters the perpendicular magnetic anisotropy, which in turn generates a torque on the magnetic layer to trigger precessional magnetization dynamics. These results provide new avenues for ultrafast manipulation of magnetization in vdW heterostructures with type-II band alignments. Lastly, we show that optically-generated spin currents from WS2 into CGT can also trigger precessional dynamics via angular momentum transfer.

Zhou, Wenyi [The Ohio State University]↗
DOE OSTI2019

Changes in Relative Fish Density Around a Deployed Tidal Turbine during on-Water Activities

Global interest in mitigating climate change effects is a driver for the development of renewable energy sources. In-stream tidal power, a type of marine hydrokinetic (MHK) energy uses tidal currents to generate electricity and is one example of developing a renewable energy industry. Effects and impacts on fishes in areas of tidal power development are a consideration, and presently there are many unanswered questions in this field of research. Knowledge of how fish use these areas before and after device installation is essential to informing regulators for decision-making. We attempted a Before-After-Control-Impact (BACI) study design to compare an index of fish density near and away from an MHK tidal energy device deployed in Cobscook Bay, Maine. The index was mean volume backscattering strength (Sv) obtained from 24-hour stationary, down-looking hydroacoustic surveys. Data were collected several times per year at an “impact” site within 50–75 m of a device and at a “control” site approximately 1.6 km away, both before and after turbine installation in August 2012. Fish density was lowest in March surveys and highest in May surveys at both sites. One of four comparisons (August 2011/before vs. 2012/after) indicated an interaction of fish density with turbine installation. Operational status of the installed turbine and on-water activity disturbances (e.g., industry vessel and diving activities) varied at the impact site and possibly influenced results. Lower fish densities were observed during installation and maintenance periods than during normal device operation. The effects of construction activities must be separated from the effects of a deployed device to effectively implement a statistically rigorous assessment that could separate the effects of these different activities. This parsimonious approach and results were used for permit licensing by federal and state regulatory bodies at this site and others and can be used to consider regulatory adjustments during different phases of device operation and maintenance.

Staines, Garrett (ORCID:0000000182829661)↗
DOE OSTI2018

Electron and Proton Acceleration in Trans-relativistic Magnetic Reconnection: Dependence on Plasma Beta and Magnetization

Nonthermal electron acceleration via magnetic reconnection is thought to play an important role in powering the variable X-ray emission from radiatively inefficient accretion flows around black holes. The trans-relativistic regime of magnetic reconnection—where the magnetization σ, defined as the ratio of magnetic energy density to enthalpy density, is ~1—is frequently encountered in such flows. By means of a large suite of two-dimensional particle-in-cell simulations, we investigate electron and proton acceleration in the trans-relativistic regime. Additionally, we focus on the dependence of the electron energy spectrum on σ and the proton β (the ratio of proton thermal pressure to magnetic pressure). We find that the electron spectrum in the reconnection region is nonthermal and can be modeled as a power law. At low β, the slope, p, is independent of β and hardens with increasing σ as $p\simeq 1.8+0.7/\sqrt{\sigma }$. Electrons are primarily accelerated by the nonideal electric field at X-points, either in the initial current layer or in current sheets generated between merging magnetic islands. At higher values of β, the electron power law steepens, and the electron spectrum eventually approaches a Maxwellian distribution for all values of σ. At values of β near β max ≈ 1/4σ, when both electrons and protons are relativistically hot prior to reconnection, the spectra of both species display an additional component at high energies, containing a few percent of particles. Finally, these particles are accelerated via a Fermi-like process by bouncing between the reconnection outflow and a stationary magnetic island

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Scattering of Radio Frequency Waves by Density Filaments

The edge region and the scrape-off layer of magnetically confined fusion devices, like tokamaks and stellarators, are replete with turbulent plasma that is a mixture of coherent, blob or filament like, structures [1] and incoherent fluctuations [2]. The variation in the density due to turbulence can be comparable to or greater than the ambient density [2]. As part of an overall effort to optimize the efficiency of operation, radio frequency (RF) waves are commonly used for heating fusion plasmas and, in tokamaks, for generating plasma current needed for confinement and controlling instabilities. The RF waves are excited by antenna structures that are placed near the wall of a fusion device. In order to deliver energy and momentum to charged particles in the core of fusion plasmas, RF waves have to propagate through the turbulent plasma. In present fusion devices, the scrap-off layer and the edge plasma region is of the order of a few centimeters. In reactor type devices, like ITER, this region is expected to be of the order of tens of centimeters. Since the efficiency of operation of a fusion reactor is of prime importance, it is imperative that we understand the effect of turbulence on RF waves. The fluctuations in density lead to changes in the plasma permittivity. As in conventional electrodynamics, the propagation of RF waves through different dielectric media is subject to reflection, refraction, and diffraction. In this paper, we summarize our theoretical and computational studies on the propagation of RF waves through filamentary structures present in the scrape-off layer.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1968

Lightweight heater generates high temperatures from low current

Double spiral molybdenum heater element uses low current, needs no insulation, and requires support only at the ends, which are also the power input points. Because there is no insulation or internal support necessary, the heater is lightweight. Its temperature potential will vary with its size and environment.

Hansen, E. L.↗
NASA NTRS1972

Fault determinations in electroexplosive devices by nondestructive techniques

Several nondestructive test techniques were developed for electroexplosive devices. The bridgewire responds, when pulsed with a safe level current, by generating a characteristic heating curve. The response is indicative of the electrothermal behavior of the bridgewire-explosive interface. Bridgewires which deviate from the characteristic heating curve were dissected and examined to determine the cause of the abnormality. Deliberate faults were fabricated into squibs. The relationship of the specific abnormality and the fault associated with it is demonstrated.

Menichelli, V. J.↗
NASA NTRS1971

Interrelationship of nondestructive testing to fault determination.

Several nondestructive test techniques have been developed for electroexplosive devices. The bridgewire will respond, when pulsed with a safe level current, by generating a characteristic heating curve. The response is indicative of the electrothermal behavior of the bridgewire-explosive interface. Bridgewires which deviate from the characteristic heating curve have been dissected and examined to determine the cause for the abnormality. Deliberate faults have been fabricated into squibs. The relationship of the specific abnormality and the fault associated with it is discussed.

Menichelli, V. J.↗
NASA NTRS1974

A test technique for measuring lightning-induced voltages on aircraft electrical circuits

The development of a test technique used for the measurement of lightning-induced voltages in the electrical circuits of a complete aircraft is described. The resultant technique utilizes a portable device known as a transient analyzer capable of generating unidirectional current impulses similar to lightning current surges, but at a lower current level. A linear relationship between the magnitude of lightning current and the magnitude of induced voltage permitted the scaling up of measured induced values to full threat levels. The test technique was found to be practical when used on a complete aircraft.

Walko, L. C.↗
NASA NTRS1974

Environmental control system development for manned spacecraft 1960-1973

This paper provides an overview of the development of environmental revitalization techniques from their beginnings in caisson and submarine habitats, up to the present time. The use of CO2 adsorbents, such as LiOH and their application to the first U.S. manned spaceflight is described, together with the beginnings of the regenerable CO2 sorber technology using molecular sieves and its ultimate application to Skylab. The concepts and hardware systems used for atmospheric revitalization on all major U.S. ground-based manned tests is detailed, including CO2 reduction and O2 generation processes. Current research and development efforts are also outlined. The paper concludes with a detailed description of the recently completed SSP, the most advanced and complete ECS that has been fabricated to date.

Popma, D. C.↗