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Thinning of field‐aligned currents
Author(s) -
Dungey J. W.
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/gl009i011p01243
Subject(s) - physics , perpendicular , convection , field (mathematics) , alfvén wave , geophysics , plasma , computational physics , wave propagation , mechanics , optics , geometry , quantum mechanics , magnetohydrodynamics , mathematics , pure mathematics
It is common to describe the field‐aligned currents associated with auroral arcs in terms of an Alfven wave propagating earthward. Taking account of convection, the wave can be stationary relative to the earth with its normal nearly perpendicular to the field. Far enough ahead of the wave linear theory is valid and here theory is restricted to both the linear and cold plasma approximations, but is sufficient to yield a significant result. This predicts that, as the wave propagates towards the earth, the wave normal becomes more nearly perpendicular to the field and the characteristic thickness decreases.