Journal article
THE TURBULENT HEATING RATE IN STRONG MAGNETOHYDRODYNAMIC TURBULENCE WITH NONZERO CROSS HELICITY
The Astrophysical journal, Vol.701(1), pp.652-657
08/10/2009
DOI: 10.1088/0004-637X/701/1/652
Abstract
Different results for the cascade power epsilon in strong, incompressible magnetohydrodynamic turbulence with nonzero cross helicity appear in the literature. In this paper, we discuss the conditions under which these different results are valid. Our conclusions can be expressed in terms of the density ρ, the rms amplitudes z+ and z− of Alfvénic fluctuations propagating parallel and antiparallel to the background magnetic field B0, and the correlation length (outer scale) measured perpendicular to B0, denoted L⊥. We argue that if z+ ≫ z− and if the z− fluctuations are sustained by the reflection of z+ fluctuations in a strong background magnetic field, then epsilon ∼ ρ(z+)2z−/L⊥ as in previous studies by Hossain, Matthaeus, Dmitruk, Lithwick, Goldreich, Sridhar, and others. On the other hand, if the minority wave type (z−) is sustained by some form of forcing that is uncorrelated with or only weakly correlated with the z+ fluctuations, then epsilon can be much less than ρ(z+)2z−/L⊥, as in previous studies by Dobrowolny, Lazarian, Chandran, and others. The mechanism for generating the minority wave type strongly affects the cascade power because it controls the coherence time for interactions between oppositely directed wave packets at the outer scale.
Details
- Title: Subtitle
- THE TURBULENT HEATING RATE IN STRONG MAGNETOHYDRODYNAMIC TURBULENCE WITH NONZERO CROSS HELICITY
- Creators
- Benjamin D. G Chandran - University of New HampshireEliot Quataert - University of California, BerkeleyGregory G Howes - University of IowaJoseph V Hollweg - University of New HampshireWilliam Dorland - University of Maryland, College Park
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.701(1), pp.652-657
- DOI
- 10.1088/0004-637X/701/1/652
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Publisher
- Institute of Physics (IOP)
- Language
- English
- Date published
- 08/10/2009
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199818702771
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