On the spectrum of magnetohydrodynamic turbulence

被引:220
作者
Boldyrev, S [1 ]
机构
[1] Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA
基金
美国国家科学基金会;
关键词
MHD; turbulence;
D O I
10.1086/431649
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We propose a phenomenological model for incompressible magnetohydrodynamic turbulence. We argue that nonlinear-wave interaction weakens as the energy cascade proceeds to small scales; however, the anisotropy of fluctuations along the large-scale magnetic field increases, which makes turbulence strong at all scales. To explain the weakening of the interaction, we propose that small-scale fluctuations of the velocity and magnetic fields become increasingly dynamically aligned as their scale decreases, so that turbulent "eddies" become locally anisotropic in the plane perpendicular to the large-scale magnetic field. In the limit of weak anisotropy, that is, weak large-scale magnetic field, our model reproduces the Goldreich-Sridhar spectrum, while the limit of strong anisotropy, that is, strong large-scale magnetic field, corresponds to the Iroshnikov-Kraichnan scaling of the spectrum. This is in good agreement with recent numerical results.
引用
收藏
页码:L37 / L40
页数:4
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