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  • 1
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    Cold streams of ionospheric oxygen in the plasma sheet during the CDAW 6 event of March 22, 1979 (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4091-409
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  • 2
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    Simultaneous observations of a theta aurora and associated magnetotail plasmas (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Observations of a transpolar arc and simultaneous measurements of associated plasmas in the magnetotail lobe on March 25, 1982, are presented. The auroral imager on board Dynamics Explorer 1 observes a theta aurora in the northern polar cap for more than two hours, between 0502 and 0720 UT. ISEE 1 is located in the southern lobe of the geomagnetic tail at a distance of 22.2 R(E) during this time. The plasma and particle detectors measure intermittent bursts of particle fluxes between 0530 and 0705 UT. The observations suggest that these particle fluxes represent the high-altitude signature of a theta aurora in the southern polar cap. The relatively dense and energetic plasmas are organized into several filamentary structures. Magnetic mapping between the two polar regions indicates that the theta aurora in the Southern Hemisphere is a mirror reflection about the noon-midnight meridional plane of the theta aurora in the Northern Hemisphere.
    Keywords: GEOPHYSICS
    Type: AD-A213768 , Journal of Geophysical Research (ISSN 0148-0227); 94; 10137-10
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  • 3
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    Spectral characteristics of plasma sheet ion and electron populations during undisturbed geomagnetic conditions (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The spectral characteristics of plasma-sheet ion and electron populations during periods of low geomagnetic activity were determined from the analysis of 127 one-hour average samples of central plasma sheet ions and electrons. Particle data from the ISEE-1 low-energy proton and electron differential energy analyzer and medium-energy particle instrument were combined to obtain differential energy spectra in the plasma sheet at geocentric radial distances above 12 earth radii. The relationships between the ion and electron spectral shapes and between the spectral shapes and the geomagnetic activity index were statistically investigated. It was found that the presence of interplanetary particle fluxes does not affect the plasma sheet particle spectral shape.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 13409-13
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  • 4
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    Boundary layer dynamics in the description of magnetospheric substorms (1988)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: This paper presents an analysis of eleven magnetospheric substorm events for which good-quality ground-based magnetometer data and ISEE satellite data were both available. It is shown that the magnetotail particle and field observations associated with a substorm expansive phase can be explained through the spatial movement of the boundary layers and central plasma sheet in the magnetotail. The sweeping of these regions past the satellite, even in the absence of temporal variations within the various regions, can lead to a set of plasma flow observations typical of what is observed in the magnetotail during substorm activity.
    Keywords: GEOPHYSICS
    Type: AD-A209803 , Journal of Geophysical Research (ISSN 0148-0227); 93; 14411-14
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  • 5
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    Energy spectra of plasma sheet ions and electrons from about 50 eV/e to about 1 MeV during plamsa temperature transitions (1988)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: ISEE-1 charged-particle measurements obtained during eight plasma temperature transitions (PTTs) in 1978-1979 are compiled in tables and graphs and analyzed in detail, comparing the ion and electron differential energy spectra with the predictions of theoretical models. PTTs are defined as approximately 1-h periods of low bulk plasma velocity and steadily increasing or decreasing thermal energy. A Maxwellian distribution is found to be inadequate in describing the PTT energy spectra, but velocity-exponential and kappa distributions are both successful, the latter especially at higher energies. The power-law index kappa varies from PTT to PTT, but the high-energy spectral index and overall shape of the distribution remain constant during a PTT; both spatial and temporal effects are observed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 93; 2562-257
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  • 6
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    Determination of the gravitational coefficent of the earth from near-earth satellites (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Laser range, Doppler, and altimeter data collected from 14 near-earth satellites have been combined to determine the value of the geocentric gravitational coefficent (GM) of the earth. A long-arc solution using three years of laser range data to Lageos was used in a separate determination in which the effects of general relativity were invetigated. The value of GM (including the mass of the atmosphere) was determined to be 398600.4405 cu km/sq sec when all corrections for general relativity are taken into account. The uncertainty (1-sigma) in the value of GM is estimated to be 0.001 cu km/sq sec.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 271-274
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  • 7
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    Three-dimensional simulation of whistler mode excited by the Spacelab 2 electron beam (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: During the Spacelab 2 mission, while an electron beam was being ejected from the Shuttle, the Plasma Diagnostics Package (PDP) detected a clear funnel-shaped emission that is believed to be caused by whistler-mode emission from the electron beam. In order to understand the mechanism of this emission, simulations with a three-dimensional partially magnetostatic code have been performed. The simulation results show that whistler-mode and lower hybrid waves are excited by the electron beam, which is initially localized in the column in the three-dimensional simulation system, and that they propagate away from the beam. The wave spectra of the electric and magnetic fields diagnosed at some points show several peaks due to the waves excited by the electron beam. The frequency range of these spectra is in qualitative agreement with the PDP data. The intense narrowband electrostatic emission near the electron plasma frequency is observed by the simulations. The simulation results show that the beam instability is responsible for the generation mechanism of these emissions.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 6855-686
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  • 8
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    Observational determination of the adiabatic index in the quiet time plasma sheet (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: An anticorrelation in the plasma density and temperature in the quiet time (AE of less than 100 nT) central plasma sheet has been demonstrated. The present results suggest that the adiabatic index is less than 1, and that earthward convecting plasma cools as it is compressed. It is pointed out that there are no observations which can presently account for the heat loss noted for the earthward convecting flux tubes of the central plasma sheet.
    Keywords: GEOPHYSICS
    Type: AD-A213766 , Geophysical Research Letters (ISSN 0094-8276); 16; 563-566
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  • 9
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    Plasma flows near the neutral sheet of the magnetotail (1987)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The Lepedea on board ISEE 1 is used to investigate the bulk flow plasma in the neutral sheet region (defined as the area where BX approx = O) of the magnetotail. For the majority of crossings there is no appreciable change in the macroscopic plasma parameters, i.e., the density, temperature and velocity of the plasma remain constant through the neutral sheet. This is true even during active periods, when AE is somewhat greater than 100nT. However, for a small number of crossings, all during disturbed times, large plasma bulk velocities abs. val V is greater than or = 300 km/s are observed. The velocity distributions during these events are qualitatively similar to those of the plasma sheet boundary layer that is usually observed at higher latitudes. The acceleration mechanism which creates the plasma sheet boundary layer extends to relatively small radial distances during these active periods.
    Keywords: GEOPHYSICS
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  • 10
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    Filamentary structures in the magnetotail lobes (1987)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The observations of plasmas which may be the source population for polar cap arcs are reported. This population consists of energetic plasma contained within filamentary structures aligned approximately parallel to the XZ plane. Using a combination of plasma, particle, and magnetic field data for several events, it is established that the filaments have their origin in the plasma sheet or its adjacent boundary layer, and that the structures protrude into the lobe region. In a number of cases, a correlation between the convection pattern and the IMF B(Z) can be inferred. This is in agreement with the observed characteristics of polar cap arcs, observations of which are correlated with a northward directed IMF. The presence of field-aligned currents suggests that field-aligned acceleration may occur between the observing satellite and earth.
    Keywords: GEOPHYSICS
    Type: AD-A180323 , Journal of Geophysical Research (ISSN 0148-0227); 92; 2349-236
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