TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 65 (No. 5), pp. 397-409, 2013

Giant pulsations as modes of a transverse Alfvénic resonator on the plasmapause

P. N. Mager and D. Yu. Klimushkin

The Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences, Irkutsk, P.O.Box 291, 664033, Russia

(Received March 21, 2012; Revised October 1, 2012; Accepted October 2, 2012; Online published June 10, 2013)

Abstract: The paper assumes that the giant pulsations are oscillations trapped within a resonator resulting from finite plasma pressure on the outer edge of the plasmapause. This resonator is bounded, across the L-shells, by two turning points allowing the wave energy to be channeled azimuthally. This assumption can explain the basic properties of the giant pulsations: strong localization across magnetic shells, poloidal polarization, presence of a significant compressional component in the Pg magnetic field, the fact that their frequency does not depend on the radial coordinate. The wave field structure both across the L-shells and along the field lines is studied. In order to explain the amplitude modulation it is sufficient to suppose that the resonator is excited by some non-stationary process. Generation by a moving source comprised of substorm-injected particles is considered.
Key words: ULF waves, giant pulsations, poloidal modes, finite β, moving source, plasmapause.

Corresponding author E-mail: p.mager@iszf.irk.ru

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