Modified magnetohydrodynamic waves in a current sheet in space
- Swedish Institute of Space Physics, Box 812, S-98128 Kiruna (Sweden)
- Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723-6099 (United States)
Large-scale coherent motions of a current sheet such as flapping or tearing of the entire current sheet are studied. The basic magnetohydrodynamic (MHD) equations are integrated over the thickness of the current sheet, and linear analysis is applied to obtain the modified dispersion relations for the MHD fast, Alfv{acute e}n, and the slow waves under non-zero background cross-sheet current. The dispersion relation for the fast and slow modes contains an imaginary part, because energy is exchanged between the wave and the background sheet current. A short-wavelength MHD slow wave propagating against/along the magnetic tension force is unstable/stable, whereas the situation is reversed for the MHD fast waves. For a thin current sheet (long-wavelength limit), the MHD slow wave becomes stagnant and very unstable, whereas the MHD fast wave propagates slowly and its stability depends on the strength of the background current. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 553019
- Journal Information:
- Physics of Plasmas, Vol. 4, Issue 12; Other Information: PBD: Dec 1997
- Country of Publication:
- United States
- Language:
- English
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