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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

Hovestadt, D.↗
NASA NTRS1979

Thin sheets of energetic electrons upstream from the earth's bow shock

ISEE spacecraft observations show that energetic (not less than 16 keV) electrons are injected into the region upstream from the earth's bow shock in a thin sheet which lies just behind the sheet of interplanetary magnetic field lines that are tangent to the shock surface. Lower energy electrons leave the shock over a much broader region. Although the energetic electron intensity varies, the sheet is nearly always present and may be a quasi-steady state feature of the bow shock. The electron velocity distribution in the thin sheet is strongly peaked and is responsible for excitation of electron plasma waves.

Anderson, K. A.↗
NASA NTRS1979

Energetic protons in the Jovian magnetosphere

Time histories, angular distributions and energy spectra of energetic protons were observed over an energy range of 0.2 to 20 MeV for the four passes of Pioneers 10 and 11 through the Jovian magnetosphere. The energetic particle data from these four passes are remarkably different. Azimuthal anisotropies appear to dominate with time variations also contributing to the very complex topology. On the inbound P-10 pass the expected corotation anisotropy was not observed in the outer magnetosphere. The simplest explanation is that the particle reference frame (the magnetospheric plasma) is moving nearly radially, suggesting the existence of a planetary wind at that time.

Mcdonald, F. B.↗
NASA NTRS1979

Simultaneous quiet time observations of energetic radiation belt protons and helium ions - The equatorial alpha/p ratio near 1 MeV

Simultaneous monitoring of energetic helium ions and protons in the earth's radiation belts has been conducted with Explorer 45 in the immediate vicinity of the equatorial plane. Protons were measured from less than 1 keV to 1.6 MeV and also above 3.3 MeV in a channel responsive up to 22 MeV; helium ions were monitored in three passbands: 910 keV to 3.15 MeV, 590 to 910 keV, and 2.0 to 3.99 MeV. Alpha/proton flux ratios were found to vary significantly with energy and location in the radiation belts. At equal energy per nucleon a range of variability for alpha/p from 0.0001 to well above 0.001 was found, and at equal energy per ion the corresponding variability was from 0.001 to above 10. The latter findings emphasize the relative importance of the very energetic helium ions in the overall radiation belt ion populations.

Fritz, T. A.↗
NASA NTRS1979

On the connection of interplanetary shock wave parameters and energetic storm particle events

A series of energetic storm particle (ESP) events is investigated on the basis of observations of energetic solar protons by IMPs IV and V between 1967 and 1972. The total number and energy of particles associated with 20 ESP events are analyzed in connection with several plasma parameters at the shock surface; i.e., magnetic and thermal pressure, magnetic field and plasma mass flux. Correlation is established between the total energy of ESPs in the energy range of 1-80 MeV and the jump in the total pressure. It is pointed out that the amount of shock energy converted to the acceleration of ESP particles is not negligible and could, in principle, contribute to the deceleration of the shock wave.

Gombosi, T.↗
NASA NTRS1979

Possible detection of energetic Jovian heavy ions at Skylab orbit

Evidence for the presence of sodium ions at a concentration about 10% that of oxygen among the particles with energies 10 to 20 MeV/nucleon seen with a detector on Skylab suggests that Jupiter is a significant source of energetic heavy particles inside the earth's magnetosphere. A numerical estimate based on the density of energetic sodium ions at 50 Jupiter radii measured on Voyager 1 indicates that the source strength is adequate.

Price, P. B.↗
NASA NTRS1979

Energetic electron bursts in the magnetopause electron layer and in interplanetary space

The magnetopause electron layer in the distant magnetotail is an annular region encircling the magnetopause in which bursts of tailward-streaming energetic (E 200 keV) electrons are almost continuously present. Sunward-streaming electron bursts with time scales and energy spectral indices similar to those of layer bursts are sometimes observed in interplanetary space upstream of the Earth. Evidence is presented to show that the layer bursts and the interplanetary bursts have a common source. With the aid of a new coordinate system, geocentric interplanetary medium coordinates, appropriate for describing the access of energetic charged particles in the inner magnetosheath to a spacecraft located in interplanetary space, it is shown that the interplanetary bursts occur predominantly on the sunward extension of the field lines associated with the magnetopause electron layer.

Bieber, J. W.↗
NASA NTRS1979

On the inference of properties of Saturn's Ring E from energetic charged particle observations

The paper demonstrates that information about Saturn's Ring E particle size is potentially obtainable from observations of Saturnian trapped radiation. It is shown that observations of the radial dependence of the intensities, energy spectra, electron-to-proton intensity ratio, and pitch angle distributions of energetic charged particles trapped outside of Ring A can potentially provide information (1) on the existence of Ring E, (2) on the effective size of the particulate matter therein, and (3) on the magnitude of the radial diffusion coefficient for energetic particles. A parametric study of these possibilities is specialized to the characteristics of the University of Iowa detectors on Pioneer 11 which was scheduled to make a close encounter with Saturn in 1979.

Thomsen, M. F.↗
NASA NTRS1980

Global zones of energetic particle precipitation

The paper identifies global zones of energetic particle precipitation in the nighttime atmosphere during disturbed magnetic conditions in rocket, satellite, and ground-based measurements. The known equatorial zone of precipitated energetic ions and neutrals is found at altitudes above 170 km, with its origin in the double-charge-exchange process of hydrogen and helium with the ring current. The flux of electrons increases linearly with altitude in the region 100-300 km and correlates with the 391.4 nm radiation intensity and magnetic activity. Finally, it is shown that the South Atlantic magnetic anomaly provides additional support for the identification of distinct low and mid-latitude zones; poleward from the plasmapause the precipitation flux is nearly isotropic and variable, and it consists of electrons and ions with the maximum intensity of the proton auroral zone occurring about 5 deg equatorward of the maximum of the electron auroral zone.

Voss, H. D.↗
NASA NTRS1980

Energetics and thermal structure of the middle atmosphere

A study of a large number of temperature measurements in the middle atmosphere shows a much more complex thermal structure of this region than described in the U.S. Standard Atmosphere, 1976. The mesopause height which is generally assumed to be at 80 km varies between 70 and 100 km, often with two minima in temperature at about 70 and 100 km and a maximum between 80-85 km. By solving the energy balance equation and the equations of continuity, the physical significance of the observed thermal structure is discussed in terms of the energetics of the various regions of the middle atmosphere. It is show that the solar UV radiation plays a major role only in the energy budget of the stratosphere and the lower thermosphere. The energetics of the mesosphere is primarily influenced by the dissipation of eddy energy. The temperature in the region is a good indicator of the eddy diffusivity and can be used in deriving the eddy diffusion coefficient.

Chandra, S.↗
NASA NTRS1980

Rocket observations of energetic ions in the nighttime equatorial precipitation zone

The paper deals with the first direct measurements of energetic particles at low altitudes in the equatorial zone. The measurements were carried out at Chilca, Peru (magnetic dip = -0.7 degrees) during the NASA launch operation Antarqui. The results illustrate how the incident energetic particle intensity, energy spectrum, and pitch-angle distribution vary with altitude in the presence of a horizontal magnetic field.

Voss, H. D.↗
NASA NTRS1980

Energetic particles in the pre-dawn magnetotail of Jupiter

A detailed account is given of the energetic electron and proton populations as observed with Voyagers 1 and 2 during their passes through the dawn magnetotail of Jupiter. The region between 20 and 150 R sub J is dominated by a thin plasma sheet, where trapped energetic electron and proton fluxes reach their maximum. Proton spectra can be represented by an exponential in rigidity with a characteristic energy of approximately 50 keV. Proton anisotropies were consistent with corotation even at 100 R sub J. A major proton acceleration event as well as several cases of field aligned proton streaming were observed. The flux of 0.4 MeV protons decreases by three orders of magnitude between 30 and 90 R sub J and then remains relatively constant to the magnetopause. Fine structure in the data indicate longitudinal asymmetries with respect to the dipole orientation. Electron spectra in the magnetosheath and interplanetary space are modulated by the Jovian longitude relative to the subsolar point.

Schardt, A. W.↗
NASA NTRS1980

Shock Sensitivity of energetic materials

Viscoplastic deformation is examined as the principal source of hot energy. Some shock sensitivity data on a proposed model is explained. A hollow sphere model is used to approximate complex porous matrix of energetic materials. Two pieces of shock sensitivity data are qualitatively compared with results of the proposed model. The first is the p2 tau law. The second is the desensitization of energetic materials by a ramp wave applied stress. An approach to improve the model based on experimental observations is outlined.

Kim, K.↗
NASA NTRS1981

Energetics of a sudden stratospheric warming simulated with a three-dimensional, spectral, quasi-geostrophic model

The energetics of a three dimensional, quasi-geostrophic simulation of a sudden stratospheric warming which developed spontaneously during an annual cycle simulation are described. Daily values of the stratospheric temperatures, zonal winds, heating rates, energies, and energy conversions are discussed and compared with those for observed warmings. It is shown that, like observed warmings, the simulated warming was preceded by an increased vertical flux of eddy kinetic energy from the troposphere and the polar heating resulted because of the strong convergence of the horizontal, eddy heat flux which was only partially balanced by adiabatic and diabatic cooling. There is a significant similarity between the energetics of the simulated and observed warmings. In addition, the warming was spontaneous and the model did not develop a major warming in each winter of the simulation. These facts suggest that this model may be useful for studying not only the warming process but also the conditions that favor its development.

Haggard, K. V.↗
NASA NTRS1980

Detection of energetic hydrogen molecules in Jupiter's magnetosphere by Voyager 2 - Evidence for an ionospheric plasma source

The discovery of energetic (approximately 1 MeV/nuc) H3 and H2 molecules in Jupiter's magnetosphere is reported. The data, obtained with the LECP instrument on Voyager 2, showed these molecules to be present throughout the magnetosphere and as far as 180 Jupiter radii from the planet, in the 'magnetospheric wind' region. Although the relative abundances of H3 and H2 do not show a monotonic trend with distance from Jupiter, the intervals of highest abundance were found in the outer magnetosphere. As an example, in the radial range 51-56 Jupiter radii, of the dayside magnetosphere, the abundances of H3 and H2 (0.60-0.95 MeV/nuc) were about 20 and 13-25% that of He, respectively, and the He abundance was about 1-2% that of H. Since H3(+) is expected to be an important constituent of Jupiter's ionosphere, the data provide strong evidence that, in addition to Io, the ionosphere may be an important local plasma source for the Jovian energetic particles. The measurements reported may represent the first detection in nature of molecules at energies as high as 1 MeV/nucleon.

Hamilton, D. C.↗
NASA NTRS1981

Interplanetary ions during an energetic storm particle event - The distribution function from solar wind thermal energies to 1.6 MeV

An ion velocity distribution function of the postshock phase of an energetic storm particle (ESP) event is obtained from data from the ISEE 2 and ISEE 3 experiments. The distribution function is roughly isotropic in the solar wind frame from solar wind thermal energies to 1.6 MeV. The ESP event studied (8/27/78) is superposed upon a more energetic particle event which was predominantly field-aligned and which was probably of solar origin. The observations suggest that the ESP population is accelerated directly out of the solar wind thermal population or its quiescent suprathermal tail by a stochastic process associated with shock wave disturbance. The acceleration mechanism is sufficiently efficient so that approximately 1% of the solar wind population is accelerated to suprathermal energies. These suprathermal particles have an energy density of approximately 290 eV cubic centimeters.

Gosling, J. T.↗
NASA NTRS1981

Earthward transport of energetic protons in the earth's plasma sheet

An analysis is made to assess the transport of energetic protons (0.29-0.50 MeV) at downstream distances of 30-45 earth radii in the earth's plasma sheet surveyed by the IMP 7 and IMP 8 spacecraft. It is found that there is a net earthward transport of these particles, although tailward streaming is observed as frequently as earthward streaming. The averaged flux is 200 per sq cm s in this energy range and the total flux over the plasma sheet region is 4 x 10 to the 22nd per s. It is suggested that this net earthward flux of energetic protons may contribute to the population of the outer radiation belt.

Lui, A. T. Y.↗
NASA NTRS1981

Sensitivity of wind analyses to barotropic energetics during summer

Three analysis schemes - the extended correction method of the University of Hawaii at Manoa (UHM), the National Meteorological Center (NMC) Hough analysis, and Sadler's subjective stream analysis (SUB) - were used to obtain grid-point winds using data for a five-day period in late summer, and barotropic energetics computations obtained using the three schemes for six limited regions in the Pacific and Indian Oceans were compared. Few differences were observed between UHM and NMC stream-function analyses, but significant differences were found in the wind fields and energetics obtained using the subjective method and the two objective methods in data-sparse regions. Major features in the local barotropic criteria field were found to be less sensitive to the analysis scheme used.

Sumi, A.↗