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  • 1
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    Observations of a free-energy source for intense electrostatic waves (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Significant progress has been made in understanding intense electrostatic waves near the upper hybrid resonance frequency in terms of the theory of multiharmonic cyclotron emission using a classical loss-cone distribution function as a model. Recent observations by Hawkeye 1 and GEOS 1 have verified the existence of loss-cone distributions in association with the intense electrostatic wave events, however, other observations by Hawkeye and ISEE have indicated that loss cones are not always observable during the wave events, and in fact other forms of free energy may also be responsible for the instability. Now, for the first time, a positively sloped feature in the perpendicular distribution function has been uniquely identified with intense electrostatic wave activity. Correspondingly, we suggest that the theory is flexible under substantial modifications of the model distribution function.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 7; May 1980
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  • 2
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    Escaping nonthermal continuum radiation (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Gurnett (1975) provided details of the continuum radiation spectrum, separating the lower frequency trapped component from an escaping component at frequencies high enough to propagate freely out of the magnetosphere and into the solar wind. The primary motivation for the present investigation is related to the new ISEE observations which show that the escaping continuum radiation differs from the trapped component in several temporal and spectral characteristics. The observations of escaping nonthermal continuum radiation are considered, taking into account spectral and temporal characteristics of escaping continuum radiation and the source region of escaping continuum radiation. Attention is given to the relationship between escaping and trapped continuum radiation, and the relationship between terrestrial escaping continuum radiation and narrowband Jovian kilometric radiation
    Keywords: GEOPHYSICS
    Type: AD-A104719 , Journal of Geophysical Research; 86; July 1
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  • 3
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    Detailed observations of the source of terrestrial narrowband electromagnetic radiation (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Detailed observations are presented of a region near the terrestrial plasmapause where narrowband electromagnetic radiation (previously called escaping nonthermal continuum radiation) is being generated. These observations show a direct correspondence between the narrowband radio emissions and electron cyclotron harmonic waves near the upper hybrid resonance frequency. In addition, electromagnetic radiation propagating in the Z-mode is observed in the source region which provides an extremely accurate determination of the electron plasma frequency and, hence, density profile of the source region. The data strongly suggest that electrostatic waves and not Cerenkov radiation are the source of the banded radio emissions and define the coupling which must be described by any viable theory.
    Keywords: GEOPHYSICS
    Type: AD-A125949 , Geophysical Research Letters; 9; Dec. 198
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  • 4
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    Direction-finding measurements of auroral kilometric radiation (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Direction-finding measurements with plasma wave experiments on the Hawkeye 1 and Imp 8 satellites are used to locate the source region of auroral kilometric radiation. This radiation has peak intensities between about 100 and 300 kHz and is emitted in intense sporadic bursts lasting for from half an hour to several hours. At peak intensity the total power emitted in this frequency range exceeds 1 billion W. The occurrence of this radiation is known to be closely associated with bright auroral arcs which occur in the local evening auroral regions. Hawkeye 1 provides direction-finding measurements of kilometric radiation from observations at high latitudes over the northern polar regions, and Imp 8 provides similar observations at large radial distances near the equatorial plane. Results from both satellites place the source of the intense auroral kilometric rdiation in the late local evening at about 22.0 hours LT and at a distance of about 0.75 earth radii from the polar axis of the earth.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 80; July 1
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  • 5
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    Electron distribution functions associated with electrostatic emissions in the dayside magnetosphere (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The analysis deals with electron distribution functions constructed from ISEE-1 dayside observations of low-energy magnetospheric electrons at low latitudes. The discussion covers some examples corresponding to three distinct types of odd half harmonic electrostatic emissions, observed in the plasma wave experiment on ISEE-1, which occur between the electron cyclotron frequency and the upper hybrid frequency.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 6; Oct. 197
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  • 6
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    A comparison of intense electrostatic waves near f-UHR with linear instability theory (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Intense electrostatic waves near the upper hybrid resonance frequency (f-UHR) have recently been detected near but beyond the plasmapause between + or -50 deg magnetic latitude at all local times. The paper shows that the electrostatic waves observed with the ISEE 1 plasma wave receiver near f-UHR are in qualitative agreement with linear theory of multicyclotron harmonic emissions. The peak amplitudes and bandwidths observed are similar to those calculated for maximum spatial growth rates. Measurements on Hawkeye of similar waves suggest that the electric field polarization is also consistent with theory. For a wide range of plasma parameters, nonconvective instability or large spatial growth rates occur within the cyclotron band encompassing the cold upper hybrid frequency.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters; 6; June 197
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  • 7
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    Intense electrostatic waves near the upper hybrid resonance frequency (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Plasma wave measurements using instruments on the Imp 6 and Hawkeye satellites are utilized in a study of very intense electrostatic waves near the upper hybrid resonance frequency in the region just outside the plasmapause. Studies of these electrostatic disturbances show that the events occur at local times and at magnetic latitudes varying from the equator to 50 deg, and the polarization of these waves is such that the wave electric field vector is oriented perpendicular to the geomagnetic field. In most cases the center frequency of the intense waves corresponds to an (n + 1/2) fg(-) harmonic near the upper hybrid resonance frequency. The hot distribution on function is described for a few events showing temperature anisotropy and a loss cone distribution. A possible mechanism for producing intense waves near the upper hybrid resonance frequency is suggested, and evidence which indicates that the intense electrostatic waves may be a source of nonthermal continuum radiation is given.
    Keywords: GEOPHYSICS
    Type: AD-A075294 , Journal of Geophysical Research; 84; Aug. 1
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  • 8
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    Generation of nonthermal continuum radiation in the magnetosphere (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Generation of electromagnetic continuum radiation from electrostatic fluctuations near the upper hybrid resonance frequency has been calculated by using cold plasma theory in an inhomogeneous plasma near the plasmapause. It is shown that both the polarization and the amplitude of electromagnetic radiation are in good quantitative agreement with spacecraft observations for nonthermal continuum radiation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research; 87; Dec. 1
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  • 9
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    Effects of chemical releases by the STS-3 Orbiter on the ionosphere (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: The Plasma Diagnostics Package, flown aboard STS-3 as part of the first Shuttle payload (OSS-1), recorded the effects of various chemical releases from the Orbiter. Changes in the plasma environment was observed during flash evaporator system releases, water dumps and maneuvering thruster operations. During flash evaporator operations, broadband Orbiter-generated electrostatic noise was enhanced and plasma density irregularities were observed to increase by 3 to 30 times with a spectrum which rose steeply and peaked below 6 Hz. In the case of water dumps, background electrostatic noise was enhanced at frequencies below about 3 kHz and suppressed at frequencies above 2 kHz. Thruster activity also stimulated electrostatic noise with a spectrum which peaked at approximately 0.5 kHz. In addition, ions with energies up to 1 keV were seen during some thruster events.
    Keywords: GEOPHYSICS
    Type: NASA-CR-171032 , NAS 1.26:171032 , U-OF-IOWA-84-5
    Format: application/pdf
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  • 10
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    Electron velocity distributions and plasma waves associated with the injection of an electron beam into the ionosphere (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An electron beam was injected into earth's ionosphere on August 1, 1985, during the flight of the Space Shuttle Challenger as part of the objectives of the Spacelab 2 mission. In the wake of the Space Shuttle a magnetically aligned sheet of electrons returning from the direction of propagation of the beam was detected with the free-flying Plasma Diagnostics Package. The thickness of this sheet of returning electrons was about 20 m. Large intensifications of broadband electrostatic noise were also observed within this sheet of electrons. A numerical simulation of the interaction of the electron beam with the ambient ionospheric plasmas is employed to show that the electron beam excites electron plasma oscillations and that it is possible for the ion acoustic instability to provide a returning flux of hot electrons by means of quasi-linear diffusion.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 6995-700
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