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标题：Rayleigh–Taylor instability of a magnetic tangential discontinuity in the presence of oscillating gravitational acceleration
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作者：M. S. Ruderman
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：615
DOI：10.1051/0004-6361/201832798
语种：English
出版社：EDP Sciences
摘要：We study the magnetic Rayleigh–Taylor (MRT) instability of a magnetohydrodynamic interface in an infinitely conducting incompressible plasma in the presence of oscillating gravity acceleration. We show that the evolution of the interface shape is described by the Mathieu equation. Written in the dimensionless form this equation contains two parameters,aandq. The parameterqcan be considered as the dimensionless wavenumber. The two parameters are related bya=Kq2, whereK, in turn, depends on the ratio of densities at the two sides of the interface,ζ, the parametersdetermining the relative magnitude of the gravity acceleration, the magnetic shear angleα, and the angleϕdetermining the direction of the perturbation wave vector. We calculate the dependence of the instability increment onqat fixedK, and the dependence onKof the maximum value of the increment with respect toq. We apply the theoretical results to the stability of a part of the heliopause near its apex point. Using the typical values of plasma and magnetic field parameters near the heliopause we obtain that the instability growth time is comparable with the solar cycle period.
关键词：Key wordseninstabilitiesmagnetohydrodynamics (MHD)plasmassolar wind