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Results for “SOLAR PLASMA”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

DEPARTURE OF HIGH-TEMPERATURE IRON LINES FROM THE EQUILIBRIUM STATE IN FLARING SOLAR PLASMAS

The aim of this study is to clarify if the assumption of ionization equilibrium and a Maxwellian electron energy distribution is valid in flaring solar plasmas. We analyze the 2014 December 20 X1.8 flare, in which the Fe xxi 187 Å, Fe xxii 253 Å, Fe xxiii 263 Å, and Fe xxiv 255 Å emission lines were simultaneously observed by the EUV Imaging Spectrometer on board the Hinode satellite. Intensity ratios among these high-temperature Fe lines are compared and departures from isothermal conditions and ionization equilibrium examined. Temperatures derived from intensity ratios involving these four lines show significant discrepancies at the flare footpoints in the impulsive phase, and at the looptop in the gradual phase. Among these, the temperature derived from the Fe xxii/Fe xxiv intensity ratio is the lowest, which cannot be explained if we assume a Maxwellian electron distribution and ionization equilibrium, even in the case of a multithermal structure. This result suggests that the assumption of ionization equilibrium and/or a Maxwellian electron energy distribution can be violated in evaporating solar plasma around 10 MK.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Observations of the solar plasma using radio scattering and scintillation methods

Observations of the solar plasma using the interplanetary scintillation technique have been made at radial distances of 0.03 to 1.2 AU. The solar wind is found to be independent of ecliptic latitude and radial distance, except close to the sun where acceleration is observed. Plasma density irregularities on a scale near the proton gyro radius, which modulate the mean density by about 1 percent, are present throughout the observed range of radial distance.

Hewish, A.↗
NASA NTRS1978

Magnetically confined plasma solar collector

The possibility of using a plasma medium for collecting solar energy in space is examined on the basis of a concept involving an orbiting magnetic bottle in which a solar-energy-absorbing plasma is confined. A basic system uses monatomic cesium as working fluid. Cesium evaporates from a source and flows into the useful volume of a magnetic bottle where it is photoionized by solar radiation. Ions and electrons lost through the loss cones are processed by a recovery system, which might be a combination of electromagnetic devices and heat engines. This study concentrates on the plasma production processes and size requirements, estimates of the magnetic field required to confine the plasma, and an estimate of the system parameters for a 10 GW solar collector using cesium.

Walters, C. T.↗
NASA NTRS1991

Multi-Spectral Solar Telescope Array. V - Temperature diagnostic response to the optically thin solar plasma

The compact soft X-ray/EUV/FUV multilayer coated telescopes developed for solar chromosphere, corona, and corona/solar-wind interface studies permit the use of conventional (Cassegrain, Herschelian, etc.) configurations. The multilayer coatings also allow a narrow-wavelength band to be selected for imaging. NASA's Multi-Spectral Solar Telescope Array is composed of 17 of these compact telescopes; attention is given to their ability to obtain temperature-diagnostic information concerning the solar plasma.

Deforest, Craig E.↗
NASA NTRS1989

A new sounding rocket payload for solar plasma studies

A sounding rocket payload developed for studies of high-temperature plasmas associated with solar active regions and flares is described. The payload instruments will record both spectra and images in the UV, EUV, and soft X-ray regions of the spectrum. The instruments, including the Dual Range Spectrograph, the Flat Field Soft X-ray Spectrograph, the Normal Incidence Soft X-ray Imager, the UV Filtergraph, and the H-alpha Imaging system, are described. Attention is also given to the new structural system of the payload, based on a large optical table suspended within the payload cavity, which will support the optical elements in their correct positions and orientations and will maintain these alignments throughout the rocket launch environment.

Bruner, Marilyn E.↗
DOE OSTI2014

Coronal heating driven by a magnetic gradient pumping mechanism in solar plasmas

The heating of the solar corona is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with a considerable magnetic gradient from the solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism to try to explain the formation of hot plasma upflows, such as hot type II spicules and hot plasma ejections. In the MGP mechanism, the magnetic gradient may drive the energetic particles to move upward from the underlying solar atmosphere and form hot upflows. These upflow energetic particles are deposited in the corona, causing it to become very hot. Rough estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km s{sup –1} in the chromosphere and about 130 km s{sup –1} in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them, and deposit them in the corona. The deposit of these energetic particles causes the corona to become hot, and the escape of such particles from the photosphere leaves it a bit cold. This mechanism can present a natural explanation to the mystery of solar coronal heating.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Simulation study of solar plasma eruptions caused by interactions between emerging flux and coronal arcade fields

We investigate the triggering mechanisms of plasma eruptions in the solar atmosphere due to interactions between emerging flux and coronal arcade fields by using two-dimensional MHD simulations. We perform parameter surveys with respect to arcade field height, magnetic field strength, and emerging flux location. Our results show that two possible mechanisms exist, and which mechanism is dominant depends mostly on emerging flux location. One mechanism appears when the location of emerging flux is close to the polarity inversion line (PIL) of an arcade field. This mechanism requires reconnection between the emerging flux and the arcade field, as pointed out by previous studies. The other mechanism appears when the location of emerging flux is around the edge of an arcade field. This mechanism does not require reconnection between the emerging flux and the arcade field but does demand reconnection in the arcade field above the PIL. Furthermore, we found that the eruptive condition for this mechanism can be represented by a simple formula.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1979

The N III and O IV intersystem multiplets as density indicators for solar plasmas

The usefulness of the relative intensities of lines within the N III intersystem multiplet near 1750 A as an electron density indicator for solar plasmas is discussed. Although the relative intensities of lines in the multiplet are density sensitive, the intensity ratios should at present be used with caution. Errors of the order of 20% in transition probabilities and excitation rate coefficients can lead to order of magnitude errors in density determinations. It is demonstrated that the intensity ratio of one of the N III intersystem lines and an allowed line from a different ion may also be used as a density indicator in the 10 to the 9th to 10 to the 11th per cu cm regime.

Feldman, U.↗