Тип публикации: статья из журнала
Год издания: 2009
Идентификатор DOI: 10.5194/angeo-27-417-2009
Ключевые слова: Magnetospheric physics, Magnetotail, MHD waves and instabilities, Plasma sheet, electric field, Gaussian method, magnetic field, magnetosphere, oscillation, plasma, wave propagation, wave velocity
Аннотация: One-fluid ideal MHD model is applied for description of current sheet flapping disturbances appearing due to a gradient of the normal magnetic field component. The wave modes are studied which are associated to the flapping waves observed in the Earth's magnetotail current sheet. In a linear approximation, solutions are obtained foПоказать полностьюr model profiles of the electric current and plasma densities across the current sheet, which are described by hyperbolic functions. The flapping eigenfrequency is found as a function of wave number. For the Earth's magnetotail conditions, the estimated wave group speed is of the order of a few tens kilometers per second. The current sheet can be stable or unstable in dependence on the direction of the gradient of the normal magnetic field component. The obtained dispersion function is used for calculation of the flapping wave disturbances, which are produced by the given initial Gaussian perturbation at the center of the current sheet and propagating towards the flanks. The propagating flapping pulse has a smooth leading front, and a small scale oscillating trailing front, because the short wave oscillations propagate much slower than the long wave ones.
Журнал: ANNALES GEOPHYSICAE
Выпуск журнала: Vol. 27, Is. 1
Номера страниц: 417-425
ISSN журнала: 09927689
Место издания: Gottingen
Издатель: Copernicus gesellschaft MBH