Ducted compressional waves in the magnetosphere in the double-polytropic approximation

被引：8
作者：
Ballai, I
Erdélyi, R
Roberts, B
机构：
[1] Univ Sheffield, Dept Appl Math, Atmosphere Res Ctr, SPARC, Sheffield S3 7RH, S Yorkshire, England
[2] Univ St Andrews, Sch Math & Stat, St Andrews KY16 9SS, Fife, Scotland
来源：
ANNALES GEOPHYSICAE | 2002年 / 20卷 / 10期
关键词：
magnetospheric physics; MHD waves and instabilities; plasma sheet; plasma waves and instabilities;
D O I：
10.5194/angeo-20-1553-2002
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
Small-amplitude compressional magnetohydro-dynamic-type waves are studied in the magnetosphere. The magnetosphere is treated as a rarefied plasma with anisotropy in the kinetic pressure distribution. The parallel and perpendicular pressures are defined by general polytropic pressure laws. This double-polytropic model can be considered as a natural extension of the magnetohydrodynamic (MHD) model when the plasma is collisionless. Generalized dispersion relations for surface and body waves are derived and analyzed for an isolated magnetic slab. The waves are confined to the slab. For specific polytropic indices, the results obtained in the (i) Chew-Goldberger-Low (CGL) double-adiabatic and (ii) double-isothermal approximations are recovered.
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页码：1553 / 1558
页数：6
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