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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The volume emissivity of type III radio bursts

The volume emissivity has been calculated for thirty-six type III solar radio bursts obtained from approximately 6.5 years of Imp 8 and ISEE 1 satellite data. Although the emissivities for these events vary over a large range, all the emissivities decrease rapidly with increasing heliocentric radial distance. The best fit power law for the emissivity, using the average power law index for all events analyzed, is J = J(0)R(-6.0), with J0 = 1.5 x 10 to the -24th W/cu m sr. This best fit emissivity is used to estimate the expected radial variation of the plasma oscillations responsible for the type III radio emissions.

Tokar, R. L.↗
NASA NTRS1980

Variability of plasma sheet dynamics

IMP 7 observations of plasma sheet structure and dynamics made during a 24-h period in which the satellite traversed the tail plasma sheet at a radial distance of 35 earth radii and remained within 2 earth radii of the expected position at the neutral sheet and in which at least five substorms occured on the ground are presented. High-time-resolution measurements of the magnetic field, plasma flow and greater than 50-keV protons obtained by the satellite and ground-based magnetic measurements are discussed for a 4-hr interval in which two small substorms occurred, a 6-hr geomagnetically quiet interval in which moderate variable plasma flows were observed, a very rapid, smooth neutral sheet crossing and earthward plasma flow during the expansion phase of a small substorm, a moderate-size substorm in which a prolonged interval of field-aligned tailward flow commenced at onset, a strong tailward and dawnward flow burst in an interval between substorms and a large substorm in which strong tailward flow was observed. Observations indicate the significant distortion of the tail field, possibly by plasma flow stresses, a neutral sheet structure occasionally resembling the hydromagnetic rotational discontinuity and a high level of magnetic turbulence during an earthward plasma flow which may contribute towards plasma sheet dissipation.

Coroniti, F. V.↗
NASA NTRS1980

Energy dependence and temporal evolution of the He-3/He-4 ratios in heavy-ion-rich energetic particle events

A study is presented of the energy dependence of the He-3/He-4 between 0.44 and 4.1 MeV per nucleon for six heavy-ion-rich events observed in 1974 and 1976. The observations were made using the low-energy dE/dx vs E Ultralow-Energy Particle telescope on IMP 8. It was found that all selected heavy-ion-rich events are also enriched in He-3: that the He-3/He-4 ratio decreases with decreasing energies; and that a rapid temporal evolution of the He-3/He-4 and the Fe/(H + He) ratios is strongly correlated during one event with the maximum value at the onset. These results are analyzed in terms of a model based on the preferential injection of He-3 and Fe resulting from turbulent ion heating and subsequent Fermi acceleration.

Moebius, E.↗
NASA NTRS1980

Observations of large fluxes of He/+/ in the solar wind following an interplanetary shock

Los Alamos Scientific Laboratory instrumentation on Imp 7 has detected large fluxes of He(+) within that volume of solar wind plasma believed to be the solar ejecta driving the interplanetary shock wave disturbance of July 29, 1977. The very high He(+)/He(++) abundance ratio of 0.3 measured during this event suggests that this was solar prominence material only partially ionized by its passage through the corona.

Gosling, J. T.↗
NASA NTRS1980

A test of two theories for the low-frequency cutoffs of nonthermal continuum radiation

A discussion and analysis of two theories that differently identify the low-frequency cutoffs of nonthermal continuum radiation are presented. The cold plasma theory and an alternate one proposed by Jones (1976) are compared experimentally with the use of continuum radiation data obtained in the outer magnetosphere by the Imp 6 and ISEE 1 spacecraft. It is found that the characteristics of this specific radiation are consistent with those expected of ordinary and extraordinary mode waves described by the cold plasma theory and it is shown that the cutoff frequencies occur at the local plasma frequency and R = 0 cutoff frequency as proposed by the same theory. The inconsistencies which were found between the Jones theory (1976) and observation are presented, and in addition no evidence is found for a component of continuum radiation propagating in the Z mode in the outer magnetosphere.

Shaw, R. R.↗
NASA NTRS1980

A survey of approximately 1 MeV/nucleon solar flare particle abundances, in the Z ? 1-26 range, during the 1973-1977 solar minimum period

The abundances of the major elements over the range H-Fe in solar flare energetic particles near 1 MeV/nucleon were surveyed for a large number of flares during the period 1973-1977; observations were carried out by the IMP 8 spacecraft in interplanetary space. The survey considered two types of solar flare events: (1) large events from which the average boundaries were deduced, and (2) events which have significant abundance differences from average. In addition, two He-3-rich events with abundance features that are different from previous examples are reported: one case with no enhancements of heavy ions, and a second case in which, compared to O, the heavy-ion enhancements are confined to the charge range Si-Fe rather than the usual case in which all elements Ne-Fe are enriched.

Mason, G. M.↗
NASA NTRS1980

Responses of the frog primary vestibular afferents to direct vibration of the semicircular canal

Responses of primary afferents (PA) of lateral semicircular canal to sinusoidal vibration of the canal wall within the range 0.05-200 Hz (mean amplitudes 5-15 microns) in immobilized frogs were studied. Dynamic characteristics (gain, phase) of relative linear velocity of the vibrator (micron X/s) were examined. At 0.2 Hz, the gain was 5.35 + or - 3.19 imp X/s /micron X/s (mean; S.D.; n=14) and linearly decreased if the frequency rose. Phase lag of relative velocity at 0.05 Hz was 49.8 deg + or - 16.5 deg (n=13) and at 1 Hz 97 deg + or - 9.4 deg (n=22). At 100 Hz phase lag was about 240 deg. Three groups of PA are described: wide range PA reacting in the range from 0.05 up to 60-180 Hz; high frequency PA responding in the range from 20-40 up to 100-150 Hz; and low frequency PA responding in the range from 0.05 up to 2-20 Hz.

Orlov, I. V.↗
NASA NTRS1981

Time and energy dependence of heavy ion abundances in solar flare energetic particle events

Examples are presented of the time and energy dependence of the abundances and spectra of the major heavy ions He, C, O and Fe during solar flare events, taken from a survey using the UMD/MPI ULET telescope on IMP-8 during 1973-1977. In some cases, time variations were found in the O/He, O/C and Fe/O ratios which appear to be inconsistent with models based solely on rigidity dependent propagation in the interplanetary medium.

Mason, G. M.↗
NASA NTRS1981

Research on solar-wind and magnetospheric electric fields and plasmas

The phenomena of particle preciptation and ion convection at high latitudes and their response to variations in the interplanetary magnetic field. Data from the low energy electron experiment and the retarding potential analyzer drift meter on Atmosphere Explorers C and D were analyzed. Additional data from the spacecraft Imp-J were utilized.

Burch, J. L.↗
NASA NTRS1981

Multiple crossings of a very thin plasma sheet in the Earth's magnetotail

High resolution magnetic field, plasma and energetic particle data from the IMP-8 spacecraft were studied for multiple crossings of the Earth's magnetotail plasma sheet when it becomes thin during magnetospheric substorms. Traversals recur on a time scale of several minutes and they are associated with high velocity plasma flows that are usually directed tailward but are occasionally directed earthward for brief intervals. Observations are explained by rapid oscillations of a plasma sheet that is only a few thousand km thick, a dimension comparable to the gyroradius of energetic protons. Differences in the angular distributions of the two energies indicate that the higher energy protons are preferentially located on field lines deeper in the tail lobe. A neutral line acceleration model is supported tailward streaming energetic electrons which are occasionally present at the lobe plasma sheet interface.

Fairfield, D. H.↗
NASA NTRS1981

Research in Space Physics at the University of Iowa

Currently active projects conducted to extend knowledge of the energetic particles and the electric, magnetic, and electromagnetic fields associated with Earth, other celestial bodies, and the interplanetary medium are summarized. These include investigations and/or instruments for Hawkeye 1; Pioneers 10 and 11; Voyagers 1 and 2; ISEE; IMP 8; Dynamics Explorer; Galileo; Spacelab and Orbital flight test missions; VLBI; and the International Solar Polar mission. Experiments and instruments proposed for the future international comet mission, the origin of plasmas in the Earth's environment mission, and the NASA active magnetospheric particle tracer experiment are mentioned.

Vanallen, J. A.↗
NASA NTRS1980

Search for characteristic features of low-energy quiet-time H, He and heavy nuclei fluxes, 1973-1977

Results of a survey of the 0.5-10 MeV/nucleon fluxes of H, He and heavier ions during interplanetary 'quiet-times' over the period 1973-1977 using the ULET telescope on IMP-8 are reported. It is found that in this energy range no characteristic flux level, or, e.g., proton/alpha ratio emerges during quiet periods in any year, thus precluding systematic long-term studies of the time behavior of the quiet-time component at these energies. Spectra for a uniquely quiet period in May 1977 and a less restrictively chosen set of quiet periods in 1976-1977 are presented and compared with previous results.

Mason, G. M.↗
NASA NTRS1980

The elemental abundances of hydrogen through nickel in the low energy cosmic rays

The relative abundances of the elements H through Ni in the galactic cosmic rays have been measured in the energy range 70-280 MeV/nucleon with the University of Chicago cosmic ray telescope on board the satellite IMP-8 from January 1973 to September 1978. Cosmic ray source abundances have been derived by extrapolating the measured composition back to the source. A key factor in the propagation calculation is the use of a pathlength distribution and a solar modulation level shown to be consistent with the secondary to primary ratios and their energy dependence below about 1 GeV/n.

Garcia-Munoz, M.↗
NASA NTRS1980

The energy dependence of the ratios of secondary to primary elements in the cosmic radiation

The secondary to primary ratios B/C, N/O and (Sc-Mn)/Fe in the galactic cosmic rays have been measured in the overall energy interval 30-180 MeV/n with the University of Chicago cosmic ray telescope on board the satellite IMP-8 during the period 1974-1978. These results, together with the values of the same ratios measured at higher energies, have been compared to the results of cosmic ray propagation calculations using different pathlength distributions (PLD) and different levels of solar modulation, in order to select a single set of parameters consistent with all the measured ratios.

Garcia-Munoz, M.↗
NASA NTRS1980

Carbon, nitrogen and oxygen isotopes in the low energy galactic cosmic rays

The isotopes of C, N, and O in the galactic cosmic rays were measured in the 45-106 Mev/nucleon range with data collected during 1973-77 by the cosmic-ray telescope onboard the IMP-7 spacecraft. The ratios of (N-15)/N, (C-13)/C, and ((O-18)/O agreed with previous measurements. Cosmic ray propagation and solar modulation indicate that the measured N isotopic ratio is in agreement with a source ratio of (N-14)/O = 0.03, which is much lower than the solar system abundance ratio.

Guzik, T. G.↗
NASA NTRS1980

The isotopic composition of neon and magnesium in the low energy cosmic rays

The ratios Ne-22/Ne-20 and Mg-26/Mg-24 were measured in galactic cosmic rays by the IMP-7 satellite in the 60 to 230 MeV/nucleon range. The neon cosmic ray source ratio Ne-22/Ne-20 is about 0.38, which is much larger than the current solar system relationship; the Mg data agrees with the solar system isotopic ratio of 0.14 at the cosmic ray source. The Ne and Mg source ratios are explained by supernova models, and become a new constraint which should be satisfied by any model of cosmic ray origin.

Garcia-Munoz, M.↗
NASA NTRS1980

Ion and electron pulses observed in the earth's magnetospheric environment

Pulses of about 100 keV ions and electrons of time duration of several minutes are frequently detected in the earth's magnetotail and in the upstream region from the earth's bow shock. The distribution of the locations of the IMP 7 satellite where the particles were observed over the period from Sept. 29, 1972 to Oct. 6, 1973 is presented. The physical implications of these findings as related to (1) the source locations and (2) the dynamic nature of the acceleration and propagation of these particles are discussed.

Lin, Y. C.↗
NASA NTRS1980

Temporal variations of the anomalous oxygen /1974-1979/ and disappearance in 1978

The temporal changes in the differential intensity and energy spectra of anomalous oxygen, and in the O/C ratios of the anomalous cosmic ray component during the 1974-79 time period were examined using data from the IMP-8 and ISEE-3 spacecrafts. In addition to the solar modulation of the intensity of anomalous oxygen, the strength of the source of this component varies, and in 1978 the anomalous component disappeared almost completely. The results disagree with the existence of a purely galactic source but are consistent with expectations based on an heliospheric origin hypothesis as formulated by Fisk et al., (1974).

Hovestadt, D.↗