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Turbulent spectra in the solar wind plasma

Published online by Cambridge University Press:  29 July 2009

DASTGEER SHAIKH  and
G. P. ZANK
DASTGEER SHAIKH
Affiliation:
Department of Physics and Center for Space Physics and Aeronomic Research (CSPAR), University of Alabama at Huntsville, Huntsville, AL 35805, USA (dastgeer.shaikh@uah.edu)
G. P. ZANK
Affiliation:
Department of Physics and Center for Space Physics and Aeronomic Research (CSPAR), University of Alabama at Huntsville, Huntsville, AL 35805, USA (dastgeer.shaikh@uah.edu)
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Abstract

Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of −5/3 over six decades in wavenumber space. A similar turbulent density spectrum in the solar wind plasma has been reported. The energy transfer process in the magnetized solar wind plasma over such extended length scales remains an unresolved paradox of modern turbulence theories, raising the especially intriguing question of how a compressible magnetized solar wind exhibits a turbulent spectrum that is a characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time-dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfvénic, supersonic and strongly magnetized plasma. It is shown that the observed Kolmogorov-like (−5/3) spectrum can develop in the solar wind plasma by supersonic plasma motions that dissipate into highly subsonic motion that passively convect density fluctuations.

Type
Papers
Information
Journal of Plasma Physics , Volume 76 , Issue 2 , April 2010 , pp. 183 - 191
Copyright
Copyright © Cambridge University Press 2009

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