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Detailed Reference Information |
Lin, C.S., Sugiura, M., Burch, J.L., Barfield, J.N. and Nielsen, E. (1984). DE 1 observations of type 1 counterstreaming electrons and field-aligned currents. Journal of Geophysical Research 89: doi: 10.1029/JA080i010p08907. issn: 0148-0227. |
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In this paper we report that the Dynamics Explorer 1 satellites detected type 1 counterstreaming electrons in the region of field-aligned currents at high altitudes in the nighttime auroral zone. Type 1 counterstreaming electrons are generally detected at energies below a few hundred electron volts in association with energetic (>keV) precipitating electron fluxes. The plasma and magnetic field measuremens from DE 1 are used to investigate the relative contributions of energetic precipitating electron fluxes and counterstreaming electrons to the field-aligned current density. The current density is computed by integrating the two-dimensional electron distribution functions in two energy ranges: 18--235 eV and 18--10,000 eV. In the case of downward current, low-energy (18<E<235 eV) electrons are found to carry more than 40% of the total plasma current density integrated above 18 eV, while higher-energy electrons carry the rest. In the case of upward currents, less than 50% of the total plasma current density integrated above 18 eV is found to be contributed by low-energy (18<E<235 eV) electrons. In general, the observed pitch angle distributions show that fluxes of counterstreaming electrons are enhanced at both small (<40¿) and large (<140¿) pitch angles. The energy spectra of counterstreaming electrons in the field-aligned directions are frequently found to be characterized by Maxwellian functions and occasionally by spectral peaks. It is thus concluded that counterstreaming electrons contribute to field-aligned current density mostly because of imbalances in the flux enhancement in the upward and downward directions. THe Scandinavian Twin Auroral Radar Experiment radar simultaneous observations indicated that the field-aligned current observed by DE 1 was closed through Pedersen currents in the ionosphere. |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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