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Ann. Geophys., 24, 1695-1704, 2006
www.ann-geophys.net/24/1695/2006/
© European Geosciences Union 2006
Oscillatory magnetic flux tube slippage in the plasma sheet
A. A. Petrukovich1, T. l. Zhang2, W. Baumjohann2, R. Nakamura2, A. Runov2, A. Balogh3, and C. Carr3
1Space Research Institute, 84/32 Profsoyuznaya st., Moscow, 117997, Russia
2Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
3The Blackett Laboratory, Imperial College London SW7 2BW, UK
Abstract. Cluster observations in the magnetotail revealed an abundance of
strongly inclined current sheets. We determine the magnetic
configuration of a particular subset of such phenomena: a series of
sheet crossings, having significantly differing inclinations
and occurring during quiet conditions. These
wave-like variations appear to propagate azimuthally and their
magnetic amplitude and magnetic gradient (current density) inside
the sheet are proportional to their steepness (degree of
inlcination). In spite of significant normal direction changes
between neighboring crossings up to 150°, the magnetic field
direction inside the neutral sheet remains almost constant. The
wavelengths and spatial amplitudes are of the order of 2–5 RE.
These observations are interpreted as crossings of a
quasi-periodic dynamical structure produced by almost vertical
slippage motion of the neighboring magnetic flux tubes in the
high-β plasma sheet, rather than large-scale flapping of a
stationary structure.
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