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Astron. Astrophys. 342, 300-310 (1999)


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Numerical simulations of nonlinear MHD body and surface waves in magnetic slabs

P. Huang 1, Z.E. Musielak 1,2,3 and P. Ulmschneider 3

1 Center for Space Plasma, Aeronomy and Astrophysics Research, University of Alabama, Huntsville, AL 35899, USA
2 Physics Department, University of Texas at Arlington, Arlington, TX 76019, USA
3 Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstrasse 15, D-69121 Heidelberg, Germany

Received 15 July 1998 / Accepted 21 October 1998

Abstract

The behavior of MHD waves propagating in magnetically structured plasmas has been extensively investigated in the literature. In most of these studies, the wave treatment was restricted to the linear regime. This paper presents the results of time-dependent and nonlinear numerical simulations of MHD body and surface waves propagating along magnetic slabs. Both longitudinal and transverse waves are computed, and the wave behavior in the linear and nonlinear regime is compared. Two physical processes are investigated in detail. The first is the energy leakage from the magnetic slab to the field-free external medium. It is found that the energy leakage is [FORMULA] for transverse slab waves, which means that the efficiency of energy transfer along the slab by these waves is significantly reduced. The second process is the excitation of MHD waves in two adjacent magnetic slabs by large amplitude acoustic waves from the external medium. The slabs have physical parameters typical for photospheric magnetic flux tubes. It is shown that only [FORMULA] of the energy carried by these acoustic waves is transferred to the slabs, and that the efficiency of this process strongly depends on the location of the slabs relative to the source of acoustic waves and on the amplitude of these waves. Both physical processes are important for the problem of heating of magnetically structured regions in the solar and stellar atmospheres.

Key words: waves – Sun: corona – Sun: chromosphere – methods: numerical – Sun: magnetic fields – MHD

Send offprint requests to: P. Ulmschneider

Correspondence to: ulm@ita.uni-heidelberg.de

© European Southern Observatory (ESO) 1999

Online publication: December 22, 1998

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