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Global structures of Alfvén‐ballooning modes in magnetospheric plasmas
Author(s) -
Vetoulis George,
Chen Liu
Publication year - 1994
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 - 10.1029/94gl01703
Subject(s) - physics , ballooning , alfvén wave , plasma , earth's magnetic field , field line , coupling (piping) , beta (programming language) , azimuth , atomic physics , computational physics , magnetic field , quantum electrodynamics , magnetohydrodynamics , nuclear physics , tokamak , quantum mechanics , optics , computer science , engineering , mechanical engineering , programming language
We show that a steep plasma pressure gradient can lead to radially localized Alfvén modes, which are damped through coupling to field line resonances. These have been called drift Alfvén ballooning modes (DABM) by [ Chen and Hasegawa , 1991] and are the prime candidates to explain Pc4–Pc5 geomagnetic pulsations observed during the recovery phase of geomagnetic storms. A strong dependence of the damping rate on the azimuthal wave number m is established, as well as on the equilibrium profile. A minimum azimuthal mode number can be found for the DABM to be radially trapped. We find that higher m DABMs are better localized, which is consistent with high‐ m observations.