Vorticity equation for MHD fast waves in geospace environment

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JA00638· OSTI ID:96501

Yamauchi, M; Lundin, R ^[1]; Lui, A T.Y. ^[2]

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1. Swedish Institute of Space Physics, Kiruna (Sweden)
2. Johns Hopkins Univ., Laurel, MD (United States)

The magnetohydrodynamic (MHD) vorticity equation is modified in order to apply it to nonlinear MHD fast waves or shocks when their extent along the magnetic field is limited. Field-aligned current (FAC) generation is also discussed on the basis of this modified vorticity equation. When the wave normal is not aligned to the finite velocity convection and the source region is spatially limited, a longitudinal polarization (u{sub {perpendicular}}{center_dot}J{sub {perpendicular}}) causes a pair of plus and minus charges inside the compressional plane waves or shocks, generating a pair of FACs. This polarization is not related to the separation between the electrons and ions caused by their difference in mass (i.e., Langmuir mode), a separation which is inherent to compressional waves. The resultant double field-aligned current structure exists both with and without the contributions from curvature drift, which is questionable in terms of its contribution to vorticity change from the viewpoint of single-particle motion. 14 refs., 3 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 96501
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A8 Vol. 98; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
EARTH MAGNETOSPHERE
GEOMAGNETIC FIELD
HYDROMAGNETIC WAVES
VORTEX FLOW
VORTICES