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Electrons in the ionospheric source cone: Evidence for runaway electrons as carriers of downward Birkeland currents
Author(s) -
Klumpar D. M.,
Heikkila W. J.
Publication year - 1982
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl009i008p00873
Subject(s) - electron , ionosphere , physics , electric field , scattering , field line , electron precipitation , pitch angle , atomic physics , magnetic field , field (mathematics) , geophysics , magnetosphere , optics , nuclear physics , mathematics , quantum mechanics , pure mathematics
Extremely intense field‐aligned fluxes of low energy electrons have been observed with ISIS‐2 streaming out of the ionosphere at auroral latitudes. Fluxes in excess of 10 10 /cm² sec ster at energies below 500 eV with peak fluxes from 10 to 100 eV were detected at 1400 km. The electrons are very strongly field‐aligned, having pitch angles confined within 10° of the magnetic field. Since they are so intense and so highly collimated they cannot be produced by atmospheric back‐scattering of a primary auroral beam. These electrons are sometimes associated with ionospheric ions that have been accelerated transverse to the magnetic field. They occur in regions of downward field‐aligned current, and may thus be carriers of the current, thus far unidentified. We suggest that they are runaway electrons from the ionosphere produced by a downward field‐aligned component of the electric field.