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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1968

Rotation of the solar wind plasma.

Sun rotation effect on azimuthal components of solar wind velocity and interplanetary magnetic field, solving angular momentum equation coupled with Maxwell equations

Alfonso-Faus, A.↗
NASA NTRS1980

Densities and mass motions in transition-zone plasmas in solar flares observed from Skylab

The electron densities and bulk motions in the transition-zone plasma of a solar flare are investigated by an analysis of EUV emission line spectra taken on Skylab. Spectra of three flares were obtained with the NRL normal incidence grating slit spectrograph in the ranges 1100-1940 and 1940-3940 A. The line ratios of transition-zone Si III lines and the intensity of the forbidden O IV 1401-A lines during flare maximum indicate electron densities on the order of 10 to the 12th/cu cm, decreasing by a factor of 2 to 3 in the flare decay phase. Line broadening of the transition-zone ions such as Si III, O IV, C IV and N V is noted, and the observed asymmetrical N V line profiles are approximated by a bi-Gaussian model of a stationary and a moving plasma component with a bulk velocity of 12 to 70 km/sec. Turbulent velocities of from 45 to 85 km/sec and from 20 to 40 km/sec are also indicated for the moving and stationary components of the transition-zone plasma, respectively.

Cheng, C.-C.↗
NASA NTRS1972

Heating of the solar flare plasma by high energy electrons.

Discussion of the heating of the ambient plasma by high-energy electrons in solar flares. It is shown that for large flares the heating is enough to produce a thermal plasma with a temperature up to 10 to the 7th K rapidly in the initial phase of the flares. Thus thermal bremsstrahlung in addition to nonthermal bremsstrahlung should be considered for the X-ray emission of solar flares in the initial phase.-

Cheng, C.-C.↗
NASA NTRS1981

Review of biased solar array - Plasma interaction studies

Possible high voltage surface interactions on the Solar Electric Propulsion System (SEPS) are examined, with particular regard for potential effects on SEPS performance. The SEPS is intended for use for geosynchronous and planetary missions, and derives power from deployed solar cell arrays which are susceptible to collecting ions and electrons from the charged and thermal particle environment of space. The charge exchange plasma which provides the thrust force can also enhance the natural charged particle environment and increase interactions between the thrust system and the biased solar array surface. Tests of small arrays have shown that snapover, where current collection becomes proportional to the panel area, can be avoided by larger cell sizes. Arcing is predicted to diminish with larger array sizes, while the problems of efflux environments are noted to be as yet undefined and require further study.

Stevens, N. J.↗
NASA NTRS1995

Observations of the 3-D distribution of interplanetary electrons and ions from solar wind plasma to low energy cosmic rays

The 3-D Plasma and Energetic Particle instrument on the GGS Wind spacecraft (launched November 1, 1994) is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. Three pairs of double-ended telescopes, each with two or three closely sandwiched passivated ion implanted silicon detectors measure electrons and ions from approximately 20 keV to greater than or equal to 300 keV. Four top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors, a large and a small geometric factor analyzer for electrons and a similar pair for ions, cover from approximately 3 eV to 30 keV. We present preliminary observations of the electron and ion distributions in the absence of obvious solar impulsive events and upstream particles. The quiet time electron energy spectrum shows a smooth approximately power law fall-off extending from the halo population at a few hundred eV to well above approximately 100 keV The quiet time ion energy spectrum also shows significant fluxes over this energy range. Detailed 3-D distributions and their temporal variations will be presented.

Lin, R. P.↗
NASA NTRS1995

The history of re-connection and the concept of the solar wind plasma with relatively small electrical conductivity

Petschek's 're-connection' model, aspiring to be universal, treated as a boundary problem meets unresolvable difficulties connected with impossibility to specify correctly boundary and initial conditions. This problem was incorrectly formulated. Hence, ineradicable logarithmic singularities occurred on the boundary surfaces. Attempts to eliminate them by incorporating the finite electrical conductivity are incorrect. This should lead to the change in the equation type, boundary condition type and in consequence to the change in solutions. Besides, the slow mode shocks cannot be driven by small internal source. As an alternative a new plasma concept is suggested. The state of fully ionized plasma in space depends completely on the entropy of the plasma heating source and on the process in which plasma is involved. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma should be very far from the thermodynamic equilibrium. Debye's screening is not complete. The excitation of the powerful resonant self-consistent electric fields in plasma provides low electric conductivity. The MHD problems should be treated in frameworks of dissipative theories.

Chertkov, A. D.↗
NASA NTRS1992

Very long baseline interferometer measurements of plasma turbulence in the solar wind

Plasma turbulence in the solar wind is investigated using angular broadening VLBI measurements at 4.99 GHz of ten extragalactic compact radio sources (quasars). The measured broadening size was corrected for intrinsic source structures which were obtained from separate VLBI observations. It was found that the measured angular sizes are considerably less than those predicted by the Erickson's (1964) empirical relationship, as well as by two other models for the strength of scattering as a function of solar elongation. However, the measurements are in good agreement with a model for the spatial power spectrum of turbulence, proposed by Coles and Harmon (1989).

Sakurai, Takayuki↗
NASA NTRS1995

Solar wind plasma periodicities observed at 1 AU by IMP 8

The IMP 8 spacecraft has been in Earth orbit since 1973, gathering plasma data over one complete 22-year solar cycle. These data are being examined to look for periodicities at time scales ranging from several hours to the entire span of the data set. A 1.3-year periodicity in the radial speed observed by IMP 8 and Voyager 2 has already been reported for the years from 1987 to 1993. The periodogram method, useful for unevenly sampled data such as the IMP 8 plasma data, has been used to search for other periods. It is interesting to note that the 13-year period is not present in the out-of-the-ecliptic component of the velocity (Vz), although a 1-year period is very obvious both visually and on the periodogram. Both components show a very strong peak associated with the 11-year solar cycle variation. This work will be extended to the thermal speed (a measure of the wind's temperature) and density, although the frequent correlations between these parameters and the velocity are expected to cause similar results. Additionally, the fine resolution data will be examined for shorter time periods than are visible using the hourly average data which are appropriate for longer periods. A comparison with periods observed at other spacecraft may also be made.

Paularena, K. I.↗
NASA NTRS1995

The transition region and coronal explorer (TRACE)

The transition region and coronal explorer (TRACE) NASA small explorer mission and instrument are presented. The TRACE scientific investigation explores the relationships between fine-scale magnetic fields and the associated solar plasma structures. The instrument collects images of solar plasmas at temperatures from 10(exp 4) to 10(exp 7) K with one arcsec spatial resolution. The design specifications of the trace instrument are presented.

Title, Alan↗
NASA NTRS1975

Heating and cooling of the thermal X-ray plasma in solar flares

Characteristic times for the heating and cooling of thermal plasma in X-ray flares are estimated from the time profile of the flare and from the temperature, emission measure and length scale of the flare-heated plasma. It is implied from the empirical values for the characteristic times that flares are produced by magnetic field reconnection; that conductive cooling of the plasma dominates radiative cooling; and that reconnection heating and conductive cooling are approximately in balance at thermal X-ray maximum.

Moore, R. L.↗
NASA NTRS1980

Study of radiatively sustained cesium plasmas for solar energy conversion

The results of a study aimed at developing a high temperature solar electric converter are reported. The converter concept is based on the use of an alkali plasma to serve as both an efficient high temperature collector of solar radiation as well as the working fluid for a high temperature working cycle. The working cycle is a simple magnetohydrodynamic (MHD) Rankine cycle employing a solid electrode Faraday MHD channel. Research milestones include the construction of a theoretical model for coupling sunlight in a cesium plasma and the experimental demonstration of cesium plasma heating with a solar simulator in excellent agreement with the theory. Analysis of a solar MHD working cycle in which excimer laser power rather than electric power is extracted is also presented. The analysis predicts a positive gain coefficient on the cesium-xenon excimer laser transition.

Palmer, A. J.↗
NASA NTRS1977

Solar wind plasma injection at the dayside magnetospheric cusp

Two mechanisms have been proposed for solar wind particle injection at the dayside magnetospheric cusps: magnetic merging and cross-field diffusion. These two mechanisms are experimentally distinguishable in that they produce different latitudinal distributions of particles penetrating to the low-altitude cusp. An examination of proton and electron measurements obtained by the AE-C satellite in the low-altitude dayside cusp reveals evidence of both types of injection processes. A majority of the injection events, especially the more intense fluxes, are best explained by a merging injection model in which cusp particles are confined to the poleward side of the last closed field line and have a characteristic energy that decreases with increasing latitudinal distance from the last closed field line. Less frequent and less intense injection events are better explained in terms of a diffusive injection of cusp particles onto closed dayside field lines with a characteristic energy that increases with increasing latitudinal distance from the last closed field line. Although diffusion appears to be quantitatively less important than merging in terms of the instantaneous particle injection rate, cross-field diffusion nevertheless appears to proceed at an unexpectedly fast rate, possibly exceeding the Bohm diffusion limit.

Reiff, P. H.↗
NASA NTRS1995

Solar wind plasma electron parameters based on aligned observations by ICE and Ulysses

During November-December 1991, the International Cometary Explorer (ICE) and Ulysses spacecraft were aligned in solar longitude, with an angular offset as small as 1 deg and a radial offset of 3.8 to 4.0 AU. Both spacecraft carry spectrometers which measure the thermal and suprathermal solar wind electron distributions. During the alignment interval, both spacecraft encountered the declining phase of a high-speed solar wind stream, representing unshocked plasma. We use the aligned observations from ICE and Ulysses to characterized the radial gradients in core and halo electron temperature, relative halo density, and heat flux, as well as the core and total polytropic indices. The thermal properties of the core vary widely in a range from isothermal to adiabatic, while the halo is more nearly isothermal. The halo density falls off more steeply for higher density plasma, and the electron heat flux gradient indicates constant or decreasing distribution skewness.

Phillips, J. L.↗