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Dispersive ducting of MHD waves in the plasma sheet: A source of Pi2 wave bursts
Author(s) -
Edwin P. M.,
Roberts B.,
Hughes W. J.
Publication year - 1986
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/gl013i004p00373
Subject(s) - atmospheric duct , substorm , wave packet , physics , magnetohydrodynamics , duct (anatomy) , plasma sheet , plasma , wave propagation , geophysics , computational physics , mechanics , magnetosphere , optics , meteorology , atomic physics , medicine , quantum mechanics , pathology , atmosphere (unit)
Fast magnetoacoustic waves can be ducted by plasma inhomogeneities such as the plasma sheet. As this ducting is dispersive an impulsive source will give rise to a well‐defined, quasi‐periodic wave packet with timescales determined by the width of the inhomogeneity and characteristic speeds in the wave duct and surrounding medium. The duration of the wave packet depends upon the distance from the source. We argue that an impulsive source in the plasma sheet at substorm onset will produce a wave packet near earth with characteristics similar to pi2 wave bursts and put this idea forward as a mechanism for the generation of pi2 pulsations.