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Nonlinear saturation of high‐m Alfvén‐ballooning modes in magnetospheric plasmas
Author(s) -
Chen Liu
Publication year - 2003
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 - 10.1029/2002gl016065
Subject(s) - physics , ballooning , saturation (graph theory) , instability , amplitude , nonlinear system , plasma , landau damping , wavenumber , magnetosphere , computational physics , wavelength , turbulence , normal mode , quantum electrodynamics , atomic physics , mechanics , quantum mechanics , tokamak , mathematics , combinatorics , vibration
A theoretical model is proposed for the nonlinear saturation of high‐m Alfvén‐ballooning instabilities in magnetospheric plasmas. Here, m is the azimuthal wave number. In the present model, a broad spectrum of Alfvén waves nonlinearly generate ion‐sound density perturbations; which, in turn, scatter the Alfvén turbulence toward lower frequencies. Balancing the linear instability growth rate with the nonlinear scattering (Landau damping) rate then yield the corresponding saturated spectrum, which tends to peak near the bottom of the eigenmode frequencies. The theory also gives estimates of wave amplitudes at saturation in reasonable agreement with satellite observations.