Onofri M, Malara F
Dipartimento di Fisica, Università della Calabria, via P. Bucci, 87036 Rende (CS), Italy.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Jul;78(1 Pt 2):016402. doi: 10.1103/PhysRevE.78.016402. Epub 2008 Jul 11.
The anisotropy properties of magnetohydrodynamic turbulence in a sheared magnetic field are analyzed through a three-dimensional numerical simulation that reproduces the linear and nonlinear stage of a tearing instability. Far from the current sheet, the energy spectrum develops perpendicularly to the local magnetic field, as in homogeneous configurations. Within the current sheet, the spectrum anisotropy is also affected by the structure of unstable modes. With increasing time, the configuration becomes more turbulent, the former effect disappears, and the energy cascade takes place perpendicularly to the local magnetic field. The local spectrum becomes increasingly anisotropic while the spatially integrated spectrum tends to isotropize. There is the possibility that these properties could be used to identify the nonlinear stage of magnetic reconnection in space and laboratory plasmas, as well as to identify the particle transport regime in the considered magnetic configuration.
通过三维数值模拟分析了剪切磁场中磁流体动力学湍流的各向异性特性，该模拟再现了撕裂不稳定性的线性和非线性阶段。远离电流片时，能谱垂直于局部磁场发展，如同在均匀构型中一样。在电流片内，谱各向异性也受不稳定模结构的影响。随着时间增加，构型变得更加湍流，前一种效应消失，能量级串垂直于局部磁场发生。局部谱变得越来越各向异性，而空间积分谱趋于各向同性。这些特性有可能用于识别空间和实验室等离子体中磁重联的非线性阶段，以及在所考虑的磁构型中识别粒子输运机制。
