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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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NASA NTRS1984

Studies of solar magnetic fields during the solar maximum year

Observations and studies of solar magnetic fields that were carried out during the period of the solar maximum year (SMY) January 1980 to June 1981, are reviewed with the goal of providing a summary of what was learned about solar magnetic fields during the SMY. Such subjects as the relationship between solar magnetic fields and flares, the role of magnetic fields in the sunspot phenomenon, the magnetic-canopy structure overlying the supergranular network as well as the turbulent magnetic fields within the network, the fields within the polar crown prominences, and the solar magnetic cycle are addressed.

Hagyard, M. J.↗
NASA NTRS1984

Solar wind and cosmic ray irradiation of grains and ices - application to erosion and synthesis of organic compounds in the solar system

Solar wind and cosmic and cosmic ray irradiation of grains induces physical and chemical effects including their erosion and the synthesis of molecular compounds within the implanted layers. The experiments performed with H2O ice implanted by keV ions are presented. The ion implantation is intended to simulate the irradiation of comets, ring grains, and satellites of outer planets, either by the primitive solar particles or by contemporary solar wind (SW) or solar cosmic rays (SCR) fluxes. The detection of molecules was obtained through in-situ infrared spectroscopy. A model is proposed for the formation of organic matter within icy solar system bodies which is in agreement with experimental results of erosion rates. The organic molecules, frozen-in within the icy mantles of the grains present in the protosolar nebula, would originate from their primitive irradiation. Such an irradiation would have taken place during an early stage of the proto-sun, when both the SW and SCR particles were more intense by orders of magnitude.

Rocard, F.↗
NASA NTRS1985

Solar maximum: Solar array degradation

The 5-year in-orbit power degradation of the silicon solar array aboard the Solar Maximum Satellite was evaluated. This was the first spacecraft to use Teflon R FEP as a coverglass adhesive, thus avoiding the necessity of an ultraviolet filter. The peak power tracking mode of the power regulator unit was employed to ensure consistent maximum power comparisons. Telemetry was normalized to account for the effects of illumination intensity, charged particle irradiation dosage, and solar array temperature. Reference conditions of 1.0 solar constant at air mass zero and 301 K (28 C) were used as a basis for normalization. Beginning-of-life array power was 2230 watts. Currently, the array output is 1830 watts. This corresponds to a 16 percent loss in array performance over 5 years. Comparison of Solar Maximum Telemetry and predicted power levels indicate that array output is 2 percent less than predictions based on an annual 1.0 MeV equivalent election fluence of 2.34 x ten to the 13th power square centimeters space environment.

Miller, T.↗
NASA NTRS1985

Solar cosmic ray bursts and solar neutrino fluxes

The neutrino flux detected in the C1-Ar experiment seems to respond to the powerful solar cosmic ray bursts. The ground-based detectors, the balloons and the satellites detect about 50% of the bursts of soalr cosmic ray generated on the Sun's visible side. As a rule, such bursts originate from the Western side of the visible solar disk. Since the solar cosmic ray bursts are in opposite phase withthe 11-year galactic cosmic ray cycle which also seems to be reflected by neutrino experiment. The neutrino generation in the bursts will flatten the possible 11-year behavior of the AR-37 production rate, Q, in the Cl-Ar experiment. The detection of solar-flare-generated gamma-quanta with energies above tens of Mev is indicative of the generation of high-energy particles which in turn may produce neutrinos. Thus, the increased Q during the runs, when the flare-generated high energy gamma-quanta have been registered, may be regarded as additional evidence for neutrino geneation in the solar flare processes.

Basilevakaya, G. A.↗
NASA NTRS1983

Solar flare particle fluences during solar cycles 19, 20 and 21

Satellite data for solar flare particle events during solar cycle 21 (up to July 1982) have been analyzed to obtain event-integrated fluxes of energetic protons and alpha particles. Thirty nine events with proton fluences (E greater than 10 MeV) greater than 10-million/sq cm occurred during 1976-1982. The average flux of protons with kinetic energy greater than 10 MeV is 65 per sq cm/s for this period. The event averaged alpha to proton ratio, in the energy interval 1-22 MeV/n, varies between 0.006 to 0.04, with an average value of about 0.02 for the whole cycle. The flux of protons (with energies greater than 10 MeV) averaged over cycle 21 is lower than those for solar-cycle 20 per sq cm/s based on satellite data, and for solar-cycle 19 378 per sq cm/s based on lunar sample data. There is no definitive correlation between solar-cycle averaged proton fluxes and sunspot numbers.

Mcguire, R. E.↗
NASA NTRS1986

Overview of Space Station attached payloads in the areas of solar physics, solar terrestrial physics, and plasma processes

This paper outlines the currently planned utilization of the Space Station to perform investigations in solar physics, solar terrestrial physics, and plasma physics. The investigations and instrumentation planned for the Solar Terrestrial Observatory (STO) and its associated Space Station accommodation requirements are discussed as well as the planned placement of the STO instruments and typical operational scenarios. In the area of plasma physics, some preliminary plans for scientific investigations and for the accommodation of a plasma physics facility attached to the Space Station are outlined. These preliminary experiment concepts use the space environment around the Space Station as an unconfined plasma laboratory. In solar physics, the initial instrument complement and associated accommodation requirements of the Advanced Solar Observatory are described. The planned evolutionary development of this observatory is outlined, making use of the Space Station capabilities for servicing and instrument reconfiguration.

Roberts, W. T.↗
NASA NTRS1986

Flat-plate solar array project. Volume 4: High-efficiency solar cells

The High Efficiency Solar Cell Task was assigned the objective of understanding and developing high efficiency solar cell devices that would meet the cost and performance goals of the Flat Plate Solar Array (FSA) Project. The need for research dealing with high efficiency devices was considered important because of the role efficiency plays in reducing price per watt of generated energy. The R&D efforts conducted during the 1982 to 1986 period are summarized to provide understanding and control of energy conversion losses associated with crystalline silicon solar cells. New levels of conversion efficiency were demonstrated. Major contributions were made both to the understanding and reduction of bulk and surface losses in solar cells. For example, oxides, nitrides, and polysilicon were all shown to be potentially useful surface passivants. Improvements in measurement techniques were made and Auger coefficients and spectral absorption data were obtained for unique types of silicon sheets. New modelling software was developed including a program to optimize a device design based on input characteristics of a cell.

Leipold, M.↗
NASA NTRS1987

Solar cycle invariance in solar wind proton temperature relationships

The relationships between solar wind proton temperature and velocity and between temperature and momentum flux density at 1 AU are examined using National Space Science Data Center IMP 8 solar wind data obtained from late 1984 to early 1985. These relationships are compared with similar ones obtained from a variety of solar wind data spanning 14 years, from 1966 to 1980. It is found that these relationships, particularly the one between temperature and velocity, are very stable over the solar cycles from which these data were drawn. This suggests that the basic physical processes which accelerate and heat the solar wind have remained unchanged for the last 20 years.

Lopez, R. E.↗
NASA NTRS1988

Solar luminosity variations in solar cycle 21

Long-term variations in the solar total irradiance found in the ACRIM I experiment on the SMM satellite have revealed a downward trend during the declining phase of solar cycle 21 of the sunspot cycle, a flat period between mid-1095 and mid-1987, and an upturn in late 1987 which suggests a direct correlation of luminosity and solar active region population. If the upturn continues into the activity maximum of solar cycle 22, a relation between solar activity and luminosity of possible climatological significance could be ascertained. The best-fit relationship for the variation of total irradiance S with sunspot number Rz and 10-cm flux F(10) are S = 1366.82 + 7.71 x 10 to the -3rd Rz and S = 1366.27 + 8.98 x 10 to the -3rd F(10)(W/sq m). These findings could be used to approximate total irradiance variations over the periods for which these indices have been compiled.

Willson, Richard C.↗
NASA NTRS1989

Isotope abundances of solar coronal material derived from solar energetic particle measurements

Coronal isotopic abundances for the elements He, C, N, O, Ne, and Mg are derived from previously published measurements of the isotopic composition of solar energetic particles by first measuring, and then correcting for, the charge-to-mass-dependent fractionation due to solar flare acceleration and propagation processes. The resulting coronal composition generally agrees with that of other samples of solar system material, but the previously noted difference between the solar flare and solar wind Ne-22/Ne-20 ratios remains unresolved.

Mewaldt, R. A.↗
NASA NTRS1989

A search for the solar roots of the most disturbed interplanetary field intervals of solar cycle 21

During the course of the Pioneer Venus Orbiter mission, fairly continuous interplanetary plasma and magnetic field data were obtained which span the interval from prior to the last solar maximum to the current solar minimum recovery. Within this nearly complete solar cycle interval, several periods of exceptional disturbance of the interplanetary field stand out. The available solar data have been examined to determine what features, if any, distinguish these periods. Neither flare nor coronal mass ejection reports show particularly unusual behavior. However, these periods appear to occur in conjunction with marked changes in the interplanetary sector structure. This suggests that heliospheric current sheet reconfiguration is an indicator of the level of interplanetary disturbance distinct from the more traditional solar activity data.

Luhmann, J. G.↗
NASA NTRS1990

Simplified Calculation Of Solar Fluxes In Solar Receivers

Simplified Calculation of Solar Flux Distribution on Side Wall of Cylindrical Cavity Solar Receivers computer program employs simple solar-flux-calculation algorithm for cylindrical-cavity-type solar receiver. Results compare favorably with those of more complicated programs. Applications include study of solar energy and transfer of heat, and space power/solar-dynamics engineering. Written in FORTRAN 77.

Bhandari, Pradeep↗
NASA NTRS1989

Determination of solar flare accelerated ion angular distributions from SMM gamma ray and neutron measurements and determination of the He-3/H ratio in the solar photosphere from SMM gamma ray measurements

Comparisons of Solar Maximum Mission (SMM) observations of gamma-ray line and neutron emission with theoretical calculation of their expected production by flare accelerated ion interactions in the solar atmosphere have led to significant advances in the understanding of solar flare particle acceleration and interaction, as well as the flare process itself. These comparisons have enabled the determination of, not only the total number and energy spectrum of accelerated ions trapped at the sun, but also the ion angular distribution as they interact in the solar atmosphere. The Monte Carlo program was modified to include in the calculations of ion trajectories the effects of both mirroring in converging magnetic fields and of pitch angle scattering. Comparing the results of these calculations with the SMM observations, not only the angular distribution of the interacting ions can be determined, but also the initial angular distribution of the ions at acceleration. The reliable determination of the solar photospheric He-3 abundance is of great importance for understanding nucleosynthesis in the early universe and its implications for cosmology, as well as for the study of the evolution of the sun. It is also essential for the determinations of the spectrum and total number of flare accelerated ions from the SMM/GRS gamma-ray line measurements. Systematic Monte Carlo calculations of the time dependence were made as a function of the He-3 abundance and other variables. A new series of calculations were compared for the time-dependent flux of 2.223 MeV neutron capture line emission and the ratio of the time-integrated flux in the 2.223 MeV line to that in the 4.1 to 6.4 MeV nuclear deexcitation band.

Lingenfelter, Richard E.↗
NASA NTRS1989

Solar nebula chemistry - Implications for volatiles in the solar system

Current theoretical models of solar nebula chemistry which take into account the interplay between chemistry and dynamics are presented for the abundant reactive volatile elements including hydrogen, carbon, nitrogen, oxygen, and sulfur. Results of these models indicate that, in the solar nebula, the dominant carbon and nitrogen gases were CO and NO, whereas, in giant planet subnebulae, the dominant carbon and nitrogen gases were CH4 and NH3; in the solar nebula, the Fe metal grains catalyzed the formation of organic compounds from CO and H2 via the Fischer-Tropsch-type reaction. It was also found that, in solar nebula, bulk FeS formation was kinetically favorable, while FeO incorporation into silicates and bulk Fe3O4 formation were kinetically inhibited. Furthermore, clathrate formation was kinetically inhibited in the solar nebula, while it was kinetically favorable in giant planet subnebulae.

Fegley, Bruce, Jr.↗
NASA NTRS1990

Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation

Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

Ajello, J. M.↗
NASA NTRS1991

A calibration of solar envelope models using the frequencies of intermediate-degree solar acoustic oscillations

The frequency dependence of the phase shift, which arises from the reflection of internal acoustic waves (p-modes) at the outer solar layers, can be determined from the accurately measured frequencies of intermediate-degree p-modes. This dependence is sensitive to the complicated structure of the outer solar layers, down to the depth of the second ionization zone of helium. It can be used to calibrate solar envelope models. The results of the direct tests of a variety of solar envelope models using the phase shift inferred from the solar oscillation frequencies are reported.

Pamiatnykh, A. A.↗
NASA NTRS1992

Concerning solar sources for Cycle 22 solar wind activity in the heliosphere

Beginning in 1989, the active phase of the present solar cycle became manifest in the outer heliosphere as large disturbances in solar wind velocity as observed by the Ames plasma analyzers aboard Pioneer 10 (46-50 AU heliocentric distance) and Pioneer 11 (about 28 AU). Inner heliospheric baseline plasma observations from the Pioneer Venus Orbiter (0.7 AU) and IMP 8 (1 AU) are useful for attempts to correlate solar events with the outer heliospheric disturbances. With regard to the onset of activity at Pioneer 11, Pioneer Venus observations are pertinent, and some of these in turn correspond with CMEs (coronal mass ejections) observed in SMM coronagraph data. In particular, enhanced solar wind speeds observed at Pioneer Venus during December 1988 to February 1989 are associated with seven large solar wind shocks (or shock candidates); corresponding CMEs may be identified. Two of these seven shocks were identified as candidates for a precursor to the onset of the disturbances at Pioneer 11. At Pioneer 10 the disturbed period includes two large disturbances, associated with the passage of shocks. There are several candidate CMEs in the SMM observations, one of which may be associated with the second Pioneer 10 shock.

Mihalov, J. D.↗
NASA NTRS1995

Ulysses solar wind plasma observations during the declining phase of solar cycle 22

Since launch in October 1990, the Ulysses mission has included an in-ecliptic cruise enroute to Jupiter encounter in February 1992 and a post-Jupiter transit through a wide range of southerly latitudes and heliocentric distances. Here we present results from the solar wind plasma experiment through June 14, 1994, at which time Ulysses was at -68.2 deg heliographic latitude. During the ecliptic phase of the mission, occurring just after solar maximum, the spacecraft encountered an irregular pattern of solar wind speed and sporadic coronal mass ejections, with mass ejections most prevalent during March 1991. Irregular, small-amplitude solar wind streams prevailed until mid-1992, after which Ulysses encountered a recurrent very high-speed stream from an equatorward extension of the South polar coronal hole. Encounters with the high-density, low-speed plasma from the coronal streamer belt ceased as Ulysses moved to increasing southerly latitudes in 1993. Many forward and reverse shocks associated with corotating interaction regions have been encountered; these shocks all had observable electron foreshocks. The shocks became less prevalent with increasing latitude, with the forward shocks disappearing first because of the tilted streamer belt and the resulting meridional shock propagation. After Ulysses passed -35 deg in July 1993 the spacecraft encountered only high-speed wind, with a speed range of 700-800 km/s and a density, scaled to 1 AU, averaging 3/cu cm. Latitudinal gradients in solar wind fluid parameters generally support previous findings, with the gradient in wind speed offset by a gradient in density such that mass momentum flux vary relatively little.

Phillips, J. L.↗