On spectral scaling laws for incompressible anisotropic magnetohydrodynamic turbulence
- Institut d'Astrophysique Spatiale, Universite de Paris-Sud, CNRS, Ba circumflex timent 121, 91405 Orsay Cedex (France)
A heuristic model is given for anisotropic magnetohydrodynamics turbulence in the presence of a uniform external magnetic field B{sub 0}e{sub parallel}. The model is valid for both moderate and strong B{sub 0} and is able to describe both the strong and weak wave turbulence regimes as well as the transition between them. The main ingredient of the model is the assumption of constant ratio at all scales between the linear wave period and the nonlinear turnover time scale. Contrary to the model of critical balance introduced by Goldreich and Sridhar [Astrophys. J. 438, 763 (1995)], it is not assumed, in addition, that this ratio be equal to unity at all scales. This allows us to make use of the Iroshnikov-Kraichnan phenomenology; it is then possible to recover the widely observed anisotropic scaling law k{sub parallel}{proportional_to}k{sub perpendicular}{sup 2/3} between parallel and perpendicular wave numbers (with reference to B{sub 0}e{sub parallel} and to obtain for the total-energy spectrum E(k{sub perpendicular},k{sub parallel}){approx}k{sub perpendicu=} l{sub ar}{sup -{alpha}}k{sub parallel}{sup -{beta}} the universal prediction, 3{alpha}+2{beta}=7. In particular, with such a prediction, the weak Alfven wave turbulence constant-flux solution is recovered and, for the first time, a possible explanation to its precursor found numerically by Galtier et al. [J. Plasma Phys. 63, 447 (2000)] is given.
- OSTI ID:
- 20764526
- Journal Information:
- Physics of Plasmas, Vol. 12, Issue 9; Other Information: DOI: 10.1063/1.2052507; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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