Oblique tearing of a thin current sheet: Implications for patchy magnetopause reconnection
- Univ. of Alaska, Fairbanks (USA)
A linear resistive tearing instability of thin magnetic reversal layer, with thickness down to the order of the ion inertial length, is analyzed under an incompressible approximation. The growth rate is calculated numerically for an oblique tearing mode exp(ik(z cos{theta} + y sin{theta})), where {theta} is the propagation angle between the wave vector k and the z axis parallel to the reversal magnetic fields. In the MHD limit, it is known that the maximally growing mode is centered about {theta} = O, and the growth rate decreases monotonically with increasing {vert bar}{theta}{vert bar}. When the finite-ion-inertial-length effect is included, the tearing instability is either enhanced or suppressed depending on the propagation angle {theta}. The authors find that only waves in several relatively narrow bands of the angle {theta} are unstable and that the unstable tearing modes become highly drifting for oblique propagations. Either the ion-inertial-length effect or the oblique propagation can lead to a vortex electric current which is responsible for magnetic field B{sub y} components normal to the tearing plane. The structure of magnetic islands is fully three dimensional and is carefully examined. Implications of the results for the patchy and intermittent reconnection of a finite-size current sheet at the dayside magnetopause are discussed.
- OSTI ID:
- 5188776
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 96:A4; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
MAGNETOPAUSE
MAGNETIC RECONNECTION
ELECTRIC CURRENTS
INSTABILITY GROWTH RATES
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
NUMERICAL SOLUTION
TEARING INSTABILITY
THICKNESS
CURRENTS
DIMENSIONS
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MAGNETIC FIELD CONFIGURATIONS
MECHANICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena