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Observational support for the current sheet catastrophe model of substorm current disruption
Author(s) -
Burkhart G. R.,
Lopez R. E.,
Dusenbery P. B.,
Speiser T. W.
Publication year - 1992
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 - 10.1029/92gl01615
Subject(s) - current sheet , physics , substorm , gyroradius , current (fluid) , plasma sheet , radius , curvature , earth radius , heliospheric current sheet , dipole , field (mathematics) , electric field , magnetic field , condensed matter physics , magnetosphere , magnetohydrodynamics , geometry , solar wind , quantum mechanics , interplanetary magnetic field , computer security , mathematics , computer science , pure mathematics , thermodynamics
It has recently been found that a one‐dimensional current sheet equilibrium with a non‐zero confection electric field, E y , and a non‐zero normal magnetic field component, B n , can reach a point of catastrophe through either the reduction of the drift velocity, υ D = cE y / B n or the increase of B n . This point of catastrophe coincides with a value of κ A ≃ 0.7, where κ A is the self‐consistent value of κ = ( R min /ρ A max ) ½ corresponding to ions of average energy. (Here R min is the minimum field‐line radius of curvature and ρ A max is the maximum gyroradius for ions of average energy.) The point of catastrophe was found to be preceded by a twisting of the current sheet field‐lines into the dawnward direction, i.e. by the development of a y ‐component of B , with odd symmetry in z , and a sign opposite B x , where positive x is earthward, positive y is in the dawn‐to‐dusk direction and positive z is northward. Since the loss of the current sheet would cause the local configuration to become more dipolar, it was suggested that the catastrophic loss of the local current sheet equilibrium could correspond to local current disruption and dipolarization. In this paper, observations of some of the signatures predicted by theory are presented.