Open AccessNonlinear instability of the geomagnetotail current sheet combining the features of tearing and cross‐field current instabilities
Author(s) -
Kropotkin A. P.,
Trubachev O. O.,
Lui A. T. Y.
Publication year - 1999
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 - 10.1029/1998ja900034
Subject(s) - instability , physics , substorm , current sheet , turbulence , microscale chemistry , two stream instability , mechanics , electron , tearing , plasma , disturbance (geology) , current (fluid) , plasma sheet , magnetohydrodynamics , computational physics , magnetosphere , quantum mechanics , paleontology , mathematics education , mathematics , biology , thermodynamics
The substorm onset instability suggested in this paper combines the features of “macroscale” electromagnetic disturbance of the tearing mode type and the “microscale” plasma turbulence, which is generated by the cross‐field current instability and modulated in coherence with the large‐scale disturbance. Both components are involved in a feedback loop. It is assumed that the current sheet (CS) is thin enough for cross‐field current instability (CCI) turbulence to already exist. Current density variations of the large‐scale disturbance result in additional CCI generation; on the other hand, that additional plasma turbulence provides in quasi‐linear approximation a flux of electrons which violates the frozen‐in condition for magnetized electrons and thus destabilizes the tearing mode. The process is nonlinear. However, the threshold amplitude diminishes as the CS thins, so that the instability sets in when the threshold gets smaller than the background fluctuations.