Тип публикации: доклад, тезисы доклада, статья из сборника материалов конференций
Конференция: International Conference on Problems of Geocosmos; St Petersburg, RUSSIA; St Petersburg, RUSSIA
Год издания: 2010
Аннотация: A linear MHD instability is investigated of the electric current sheet characterized by a small normal magnetic field component B-z varying along the sheet. The tangential magnetic field component, B-x, is modeled by a hyperbolic function describing Harris-like variations of the field across the sheet. This work is an extended numerical study of the so called "double gradient instability" which was analyzed previously in the framework of the simplified analytical approach for an incompressible plasma. For this problem, formulated in 3D domain, the conventional compressible ideal MHD equations are applied. By assuming Fourier harmonics along the electric current, the linearized 3D equations have been reduced to 2D ones. A finite difference numerical scheme is applied to examine the time evolution of small initial perturbations of the equilibrium background. Finally, dispersion curve is obtained for the kink-like mode of the instability. It is shown that this curve demonstrates a quantitative agreement with the previous theoretical results, obtained in the frame of a 1D incompressible model. The dependence of the instability growth rates on the magnetic gradient partial derivative B-z/partial derivative x is examined, demonstrating a good agreement with the theoretical predictions. However, the numerical growth rates are somewhat less than the analytical ones by a factor depending, probably, on a ratio of the acoustic and Alfven speeds. This dependence is a subject of our future study.
Журнал: PROCEEDINGS OF THE 8TH INTERNATIONAL CONFERENCE PROBLEMS OF GEOCOSMOS
Номера страниц: 132-136
Место издания: ST PETERSBURG
Издатель: ST PETERSBURG STATE UNIV, FAC PHYSICS
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