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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Magnetic Causes of Solar Coronal Mass Ejections: Dominance of the Free Magnetic Energy Over the Magnetic Twist Alone

We examine the magnetic causes of coronal mass ejections (CMEs) by examining, along with the correlations of active-region magnetic measures with each other, the correlations of these measures with active-region CME productivity observed in time windows of a few days, either centered on or extending forward from the day of the magnetic measurement. The measures are from 36 vector magnetograms of bipolar active regions observed within -30" of disk center by the Marshal Space Flight Center (MSFC) vector magnetograph. From each magnetogram, we extract six whole-active-region measures twice, once from the original plane-of-the-sky magnetogram and again a h r deprojection of the magnetogram to disk center. Three of the measures are alternative measures of the total nonpotentiality of the active region, two are alternative measures of the overall twist in the active-region's magnetic field, and one is a measure of the magnetic size of the active region (the active region's magnetic flux content). From the deprojected magnetograms, we find evidence that (1) magnetic twist and magnetic size are separate but comparably strong causes of active-region CME Productivity, and (2) the total free magnetic energy in an active region's magnetic field is a stronger determinant of the active region's CME productivity than is the field's overall twist (or helicity) alone. From comparison of results from the non-deprojected magnetograms with corresponding results from the deprojected magnetograms, we find evidence that (for prediction of active-region CME productivity and for further studies of active-region magnetic size as a cause of CMEs), for active regions within approx.30deg of disk center, active-region total nonpotentiality and flux content can be adequately measured from line-of-sight magnetograms, such as from SOH0 MDI.

Falconer, D. A.↗
DOE OSTI2024

Conversion of Magnetic Energy to Plasma Kinetic Energy During Guide Field Magnetic Reconnection in the Laboratory

Here, we present laboratory measurements showing the two-dimensional (2D) structure of energy conversion during magnetic reconnection with a guide field over the electron and ion diffusion regions, resolving the separate energy deposition on electrons and ions. We find that the electrons are energized by the parallel electric field at two locations, at the X line and around the separatrices. On the other hand, the ions are energized ballistically by the perpendicular electric field in the vicinity of the high-density separatrices. An energy balance calculation by evaluating the terms of the Poynting theorem shows that 40% of the magnetic energy is converted to particle energy, 2/3 of which is transferred to ions and 1/3 to electrons. Further analysis suggests that the energy deposited on particles manifests mostly in the form of thermal kinetic energy in the diffusion regions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Magnetic Energy Conversion in Magnetohydrodynamics: Curvature Relaxation and Perpendicular Expansion of Magnetic Fields

Abstract The mechanisms and pathways of magnetic energy conversion are an important subject for many laboratory, space, and astrophysical systems. Here, we present a perspective on magnetic energy conversion in magnetohydrodynamics through magnetic field curvature relaxation (CR) and perpendicular expansion (PE) due to magnetic pressure gradients, and quantify their relative importance in two representative cases, namely 3D magnetic reconnection and 3D kink-driven instability in an astrophysical jet. We find that the CR and PE processes have different temporal and spatial evolutions in these systems. The relative importance of the two processes tends to reverse as the system enters the nonlinear stage from the instability growth stage. Overall, the two processes make comparable contributions to magnetic energy conversion, with the PE process somewhat stronger than the CR process. We further explore how these energy conversion terms can be related to particle energization in these systems.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Thermodynamics of energy magnetization

We construct the thermodynamics of energy magnetization in the presence of gravitomagnetic field. We show that the free energy must be modified to account for the modification of the energy current operator in the presence of a confining potential. The explicit expression of the energy magnetization is derived for a periodic system, and the Streda formula for the thermal Hall conductivity is rigorously established. Furthermore, we demonstrate our theory of the energy magnetization and the Streda formula in a Chern insulator.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2018

Lunar Superconducting Magnetic Energy Storage (LSMES)

Superconducting Magnetic Energy Storage (SMES) is an energy storage system that stores electrical energy in the form of a magnetic field by passing direct current through a superconducting coil. The conductor for carrying the current operates at cryogenic temperatures where it becomes a superconductor and thus has virtually no resistive losses as it produces the magnetic field. [1]. The energy can be stored in a persistent mode until required [2]. The main terrestrial challenge for SMES is the need for a cryo-cooling system and the cost associated with its deployment, operation and maintenance. For lunar and planetary exploration, this challenge is totally mitigated using the cold environment of the mission to sustain superconductivity temperatures. The permanently shadowed craters on the moon have regolith temperatures between 50-60K (3), which is the operating temperature for High Temperature Superconducting (HTS) wire. SMES provides several ad-vantages over traditional chemical batteries that: 1) incur much energy loss in extremely cold environments due to power needed for heaters, 2) are inefficient due to their inherent redox and side reactions, and 3) fail over time due to charge/discharge cycling changes in their chemical processes.

Evans, M. E.↗
NASA NTRS2006

Magnetic Causes of Solar Coronal Mass Ejections: Dominance of the Free Magnetic Energy over Either the Magnetic Twist or Size Alone

We report further results from our ongoing assessment of magnetogram-based measures of active-region nonpotentiality and size as predictors of coronal mass ejections (CMEs). We have devised improved generalized measures of active-region nonpotentiality that apply to active regions of any degree of magnetic complexity, rather than being limited to bipolar active regions as our initial measures were. From a set of approx.50 active-regions, we have found that measures of total nonpotentiality have a 75-80% success rate n predicting whether an active region will produce a CME in 2 days after the magnetogram. This makes measures of total nonpotentiality a better predictor than either active-region size, or active region twist (size-normalized nonpotentiality), which have a approx.65% success rates. We have also found that we can measure from the line-of-sight magnetograms an active region's total nonpotentiality and the size, which allows use to use MDI to evaluate these quantities for 4-5 consecutive days for each active region, and to investigate if there is some combination of size and total nonpotentiality that have a stronger predictive power than does total nonpotentiality. This work was funded by NASA through its LWS TR&T Program and its Solar and Heliospheric Physics SR&T Program, and by NSF through its Solar Terrestrial Research and SHINE programs.

Falconer, D. A.↗
NASA NTRS2012

Magnetic Energy and Helicity in Two Emerging Active Regions in the Sun

The magnetic energy and relative magnetic helicity in two emerging solar active regions, AR 11072 and AR 11158,are studied. They are computed by integrating over time the energy and relative helicity fluxes across the photosphere. The fluxes consist of two components: one from photospheric tangential flows that shear and braid field lines (shear term), the other from normal flows that advect magnetic flux into the corona (emergence term). For these active regions: (1) relative magnetic helicity in the active-region corona is mainly contributed by the shear term,(2) helicity fluxes from the emergence and the shear terms have the same sign, (3) magnetic energy in the corona (including both potential energy and free energy) is mainly contributed by the emergence term, and(4) energy fluxes from the emergence term and the shear term evolved consistently in phase during the entire flux emergence course.We also examine the apparent tangential velocity derived by tracking field-line footpoints using a simple tracking method. It is found that this velocity is more consistent with tangential plasma velocity than with the flux transport velocity, which agrees with the conclusion by Schuck.

HELICITY↗
NASA NTRS1972

Magnetic energy flow in the solar wind.

Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

Modisette, J. L.↗
NASA NTRS1976

On build-up of magnetic energy in the solar atmosphere

The dynamic response of the solar atmosphere is examined with the use of self-consistent numerical solutions to the complete set of nonlinear two-dimensional hydromagnetic equations. Of particular interest are the magnetic-energy buildup and the velocity field established by emerging flux at the base of an existing magnetic loop structure in a stationary atmosphere. For a plasma with a relatively low beta (0.03), the magnetic-energy buildup is approximately twice that of the kinetic energy, while the buildup in magnetic energy first exceeds but is eventually overtaken by the kinetic energy for a plasma with an intermediate beta (3). The increased magnetic flux causes the plasma to flow upward near the loop center and downward near the loop edges for the low-beta plasma. The plasma eventually flows downward throughout the lower portion of the loop carrying the magnetic field with it for the intermediate beta plasma. It is hypothesized that this latter case, and possibly the other case as well, may provide a reasonable simulation of the disappearance of prominences by flowing down into the chromosphere (a form of disparition brusque).

Nakagawa, Y.↗
DOE OSTI2025

Electron-Only Magnetic Reconnection and Inverse Magnetic-Energy Transfer at Subion Scales

We derive, and validate numerically, an analytical model for electron-only magnetic reconnection applicable to strongly magnetized plasmas. Our model predicts subion-scale reconnection rates significantly higher than those pertaining to large-scale reconnection, aligning with recent observations and simulations. Here, we apply this reconnection model to the problem of inverse magnetic energy transfer at subion scales. We derive time-dependent scaling laws for the magnetic energy decay and the typical magnetic structure dimensions that differ from those previously found in the magnetohydrodynamics regime. These scaling laws are validated via two- and three-dimensional simulations, demonstrating that subion-scale magnetic fields can reach large, system-size scales via successive coalescence.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Integration of Superconducting Magnetic Energy Storage (SMES) Systems Optimized with Second-Generation, High-Temperature Superconducting (2G-HTS) Technology with a Major Fossil-Fueled Asset

Utility companies and fossil fueled generation assets are seeking combinations of “hybrid energy storage” to allow power to be provided in advance of, and to otherwise complement, peaking natural gas-fired generation. American Maglev Technology of Florida Inc. (AMT) learned during the Phase I program based on interactions with NRG Energy (NRG) that energy storage such as superconducting magnetic energy storage (SMES) can qualify as a Black Start unit in most markets, ensuring orderly re-start of grid operations and fossil fueled power plants and serving as an important asset of hybrid energy storage technology. In conjunction with the University of Houston (UH), AMT and NRG are working together to scale up low-cost, high- efficiency, second-generation high-temperature superconducting (2G-HTS) technology for deployment across several markets, with a primary focus on the commercial development of utility grid-scale SMES (g-SMES) systems. Ultimately the program confirmed that the novel g-SMES design can meet the performance and financial requirements of the fossil power plant industry, while exhibiting continuous grid-voltage regulation; cost-effective, peak-hour energy storage with almost infinite life; increased input/output efficiency; and the capability to undergo millions of charging cycles, without degradation, representing a significant improvement over lithium ion and other conventional storage technologies. We believe wide scale deployment of this technology is feasible and practical when compared to the higher life cycle cost and relatively short lifespan of chemical batteries. Based on these findings, the future for deployment of SMES at many fossil-fueled power plants exceeding 100MW capability is bright. Further de-risking g-SMES technology would pave the way for the construction of a subscale prototype. Eventually, scaled-down versions of SMES are expected to be competitive with the multi-billion-dollar lithium-ion market for a wide range of commercial, industrial, and transportation uses. There is long-term potential for commercialization and widespread deployment of this disruptive technology, which would spawn a new worldwide supply chain and create domestic, high-tech manufacturing jobs in the green industry.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS1988

Evidence that magnetic energy shedding in solar filament eruptions is the drive in accompanying flares and coronal mass ejections

The dependence of the magnetic energy on the field expansion and untwisting of the flux tube in which an erupting solar filament is embedded has been determined in order to evaluate the energy decrease in the erupting flux tube. Magnetic energy shedding by the filament-field eruption is found to be the driving mechanism in both filament-eruption flares and coronal mass ejections. Confined filament-eruption flares, filament-eruption flares with sprays and coronal mass ejections, and coronal mass ejections from quiescent filament eruptions are all shown to be similar types of events.

Moore, Ronald L.↗
NASA NTRS2010

A Tool for Empirical Forecasting of Major Flares, Coronal Mass Ejections, and Solar Particle Events from a Proxy of Active-Region Free Magnetic Energy

This presentation describes a new forecasting tool developed for and is currently being tested by NASA s Space Radiation Analysis Group (SRAG) at JSC, which is responsible for the monitoring and forecasting of radiation exposure levels of astronauts. The new software tool is designed for the empirical forecasting of M and X-class flares, coronal mass ejections, as well as solar energetic particle events. Its algorithm is based on an empirical relationship between the various types of events rates and a proxy of the active region s free magnetic energy, determined from a data set of approx.40,000 active-region magnetograms from approx.1,300 active regions observed by SOHO/MDI that have known histories of flare, coronal mass ejection, and solar energetic particle event production. The new tool automatically extracts each strong-field magnetic areas from an MDI full-disk magnetogram, identifies each as an NOAA active region, and measures a proxy of the active region s free magnetic energy from the extracted magnetogram. For each active region, the empirical relationship is then used to convert the free magnetic energy proxy into an expected event rate. The expected event rate in turn can be readily converted into the probability that the active region will produce such an event in a given forward time window. Descriptions of the datasets, algorithm, and software in addition to sample applications and a validation test are presented. Further development and transition of the new tool in anticipation of SDO/HMI is briefly discussed.

Barghouty, A. F.↗
NASA NTRS2009

The Maximum Free Magnetic Energy Allowed in a Solar Active Region

Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is ~1, and (2) any one CME/flare eruption releases no more than a small fraction (less than ~10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

Moore, Ronald L.↗
NASA NTRS1988

High temperature superconducting magnetic energy storage for future NASA missions

Several NASA sponsored studies based on 'conventional' liquid helium temperature level superconductivity technology have concluded that superconducting magnetic energy storage has considerable potential for space applications. The advent of high temperature superconductivity (HTSC) may provide additional benefits over conventional superconductivity technology, making magnetic energy storage even more attractive. The proposed NASA space station is a possible candidate for the application of HTSC energy storage. Alternative energy storage technologies for this and other low Earth orbit missions are compared.

Faymon, Karl A.↗