Journal article
A Model of Turbulence in Magnetized Plasmas: Implications for the Dissipation Range in the Solar Wind
Journal of Geophysical Research: Space Physics, Vol.113(A5), pp.A05103-n/a
07/20/2007
DOI: 10.1029/2007JA012665
Abstract
J. Geophys. Res. 113, A05103 (2008) This paper studies the turbulent cascade of magnetic energy in weakly
collisional magnetized plasmas. A cascade model is presented, based on the
assumptions of local nonlinear energy transfer in wavenumber space, critical
balance between linear propagation and nonlinear interaction times, and the
applicability of linear dissipation rates for the nonlinearly turbulent plasma.
The model follows the nonlinear cascade of energy from the driving scale in the
MHD regime, through the transition at the ion Larmor radius into the kinetic
Alfven wave regime, in which the turbulence is dissipated by kinetic processes.
The turbulent fluctuations remain at frequencies below the ion cyclotron
frequency due to the strong anisotropy of the turbulent fluctuations,
k_parallel << k_perp (implied by critical balance). In this limit, the
turbulence is optimally described by gyrokinetics; it is shown that the
gyrokinetic approximation is well satisfied for typical slow solar wind
parameters. Wave phase velocity measurements are consistent with a kinetic
Alfven wave cascade and not the onset of ion cyclotron damping. The conditions
under which the gyrokinetic cascade reaches the ion cyclotron frequency are
established. Cascade model solutions imply that collisionless damping provides
a natural explanation for the observed range of spectral indices in the
dissipation range of the solar wind. The dissipation range spectrum is
predicted to be an exponential fall off; the power-law behavior apparent in
observations may be an artifact of limited instrumental sensitivity. The
cascade model is motivated by a programme of gyrokinetic simulations of
turbulence and particle heating in the solar wind.
Details
- Title: Subtitle
- A Model of Turbulence in Magnetized Plasmas: Implications for the Dissipation Range in the Solar Wind
- Creators
- Gregory G Howes - University of California, BerkeleySteven C Cowley - Imperial College LondonWilliam Dorland - University of Maryland, College ParkGregory W Hammett - Princeton Plasma Physics LaboratoryEliot Quataert - University of California, BerkeleyAlexander A Schekochihin - Imperial College London
- Resource Type
- Journal article
- Publication Details
- Journal of Geophysical Research: Space Physics, Vol.113(A5), pp.A05103-n/a
- DOI
- 10.1029/2007JA012665
- ISSN
- 0148-0227
- eISSN
- 2156-2202
- Language
- English
- Date published
- 07/20/2007
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199677402771
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