Interaction of propagating magnetosonic and Alfvén waves in a longitudinally inhomogeneous plasmaстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 6 декабря 2018 г.
Аннотация:The field line resonance theory has turned out to be very successful in the
interpretation of the occurrence of narrow-band ULF waves at middle and auroral
latitudes. However, observational evidence has emerged (such as the occurrence of
monochromatic Pc3 waves deep in the polar cap, Pi1B pulsations associated with tail
plasma flows, and ULF waves in the magnetospheres of giant planets) which indicates that
some basic assumptions of this theory may be insufficient in regions with open or very
extended field lines. To interpret these observations, we suggest a model describing the
interaction of propagating magnetosonic and Alfve?n waves in longitudinally
inhomogeneous plasma. A set of equations for the amplitudes of the interacting modes with
account of finite frequency effect is obtained and investigated in the WKB approximation.
In the synchronization region, where the wave vectors of the two modes approach one
another, a substantial part of the fast magnetosonic wave energy is converted into the
Alfve?n wave energy. The phases of the waves are matched in such a way that the phase
difference is most favorable for wave conversion. This conversion has a resonant character
which may explain the occurrence of monochromatic waves with frequencies much higher
than the field line eigenfrequency.