Open AccessPhysics of the explosive growth phase: Ballooning instability revisited
Author(s) -
Liu W. William
Publication year - 1997
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/96ja03561
Subject(s) - ballooning , instability , explosive material , physics , gyroradius , plasma , wavenumber , current sheet , magnetohydrodynamics , mechanics , plasma sheet , curvature , two stream instability , pressure gradient , magnetosphere , classical mechanics , tokamak , optics , nuclear physics , geometry , chemistry , organic chemistry , mathematics
In situ observations have led to the notion of the explosive growth phase when the crosstail current sheet inside L∼10 suddenly thins in a time of ∼1 min. A theoretical explanation of the current intensification envisages the ballooning instability of magnetospheric plasma. In this paper, this theoretical notion is reanalyzed mathematically. In contrast to some previous work, we find that for a high‐plasma, the ballooning instability can be excited easily by an earthward pressure gradient of any magnitude and for perturbations having parallel wavenumbers comparable to the field line curvature. The instability is compounded by its own development, leading ultimately to the extreme condition of a thin current sheet of a few ion gyroradius thick.