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Sketch of a unifying auroral theoryOn the basis of field and particle observations, it is suggested that a bright auroral display is a part of a magnetosphere-ionosphere current system which is fed by a charge-separation process in the outer magnetosphere (or the solar wind). The upward magnetic-field-aligned current is flowing out of the display, carried mainly by down-flowing electrons from the hot-particle populations in the outer magnetosphere (the ambient cold electrons being depleted at high altitudes). As a result of the magnetic mirroring of these downflowing current carriers, a large potential drop is set up along the magnetic field, increasing both the number flux and the kinetic energy of the precipitating electrons. It is found that this simple basic model, when combined with wave-particle interactions, may be able to explain a highly diversified selection of auroral particle observations. It may thus be possible to explain both inverted-V events and auroral rays in terms of a static parallel electric field, and the electric field may be compatible with a strongly variable pitch-angle distribution of the precipitating electrons, including distributions peaked at 90 deg as well as 0 deg. This model may also provide a simple explanation of the simultaneous precipitation of electrons and collimated positive ions.
Document ID
19760015701
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Lennartsson, W. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
September 3, 2013
Publication Date
November 1, 1975
Subject Category
Geophysics
Report/Patent Number
NASA-TM-X-64998
Accession Number
76N22789
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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