Auroral Electron Beams near the Magnetic Equator
Intense beams of electrons travelling parallel to the local magnetic field have been observed at a magnetic latitude of 11° and a radial distance of 6.6 Re. The distribution function for electrons travelling within 8° of the field line direction is typically flat or slightly rising up to a break point beyond which it decreases as v−5 to v−10. The energy corresponding to the break point velocity is usually between 0.1 and 10 keV. These beams are found to occur on closed field lines at the inner edge of the plasma sheet and thus at the root of the earth’s magnetotail. Beams with break point energies greater than 2 k seem to occur only within the first 10 minutes after the onset of hot plasma injection associated with a magnetospheric substorm. Although the origin and destiny of these electrons is as yet unknown, considerations of the total energy and the number of particles transported guarantee that they must play a dominant role in many key magnetospheric processes.
KeywordsPitch Angle Plasma Sheet Magnetic Field Direction Magnetic Equator Parallel Electric Field
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