Scaling Laws of Turbulence and Heating of Fast Solar Wind: The Role of Density Fluctuations
- Dipartimento di Fisica, Universita della Calabria, Ponte Bucci 31C, I-87036 Rende (Italy)
- Liquid Crystal Laboratory, INFM/CNR, Ponte Bucci 33B, I-87036 Rende (Italy)
- University of Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France)
- Istituto di Fisica dello Spazio Interplanetario-INAF, via Fosso del Cavaliere Roma (Italy)
Incompressible and isotropic magnetohydrodynamic turbulence in plasmas can be described by an exact relation for the energy flux through the scales. This Yaglom-like scaling law has been recently observed in the solar wind above the solar poles observed by the Ulysses spacecraft, where the turbulence is in an Alfvenic state. An analogous phenomenological scaling law, suitably modified to take into account compressible fluctuations, is observed more frequently in the same data set. Large-scale density fluctuations, despite their low amplitude, thus play a crucial role in the basic scaling properties of turbulence. The turbulent cascade rate in the compressive case can, moreover, supply the energy dissipation needed to account for the local heating of the nonadiabatic solar wind.
- OSTI ID:
- 21370622
- Journal Information:
- Physical Review Letters, Vol. 103, Issue 6; Other Information: DOI: 10.1103/PhysRevLett.103.061102; (c) 2009 The American Physical Society; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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