In situ multi-satellite detection of coherent vortices as a manifestation of Alfvénic turbulence.
Turbulence in fluids and plasmas is a ubiquitous phenomenon driven by a variety of sources-currents, sheared flows, gradients in density and temperature, and so on. Turbulence involves fluctuations of physical properties on many different scales, which interact nonlinearly to produce self-organized structures in the form of vortices. Vortex motion in fluids and magnetized plasmas is typically governed by nonlinear equations, examples of which include the Navier-Stokes equation, the Charney-Hasegawa-Mima equations and their numerous generalizations. These nonlinear equations admit solutions in the form of different types of vortices that are frequently observed in a variety of contexts: in atmospheres, in oceans and planetary systems, in the heliosphere, in the Earth's ionosphere and magnetosphere, and in laboratory plasma experiments. Here we report the discovery by the Cluster satellites of a distinct class of vortex motion-short-scale drift-kinetic Alfvén (DKA) vortices-in the Earth's magnetospheric cusp region. As is the case for the larger Kelvin-Helmholtz vortices observed previously, these dynamic structures should provide a channel for transporting plasma particles and energy through the magnetospheric boundary layers.
Sundkvist
David
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Laboratoire de Physique et Chimie de l'Environnement, CNRS, 45071 Orléans, France. davids@irfu.se
Krasnoselskikh
Vladimir
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Shukla
Padma K
PK
Vaivads
Andris
A
André
Mats
M
Buchert
Stephan
S
Rème
Henri
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