Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow
Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow
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DOI：
10.1063/1.2716669
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发表时间：
2007-04
影响因子：
2.2
通讯作者：
A. Ishizawa;N. Nakajima
中科院分区：
文献类型：
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作者：
A. Ishizawa;N. Nakajima
这是第一个数值模拟表明，一个宏磁流体动力学（macro-MHD）模式被激发作为多尺度相互作用的结果，在准稳态平衡所形成的微湍流和带状流之间的平衡的基础上减少两种流体模型。这种模拟的宏观MHD模式，双撕裂模式，是在一个反向剪切平衡，包括纬向流和湍流由于动力气球模式。在准定常平衡中，具有与双撕裂模相同螺旋度的宏观尺度涨落是湍流的一部分。经过一段时间后，宏观MHD模式开始增长。它有效地利用了平衡电流密度梯度的自由能，并通过纬向流抑制和磁岛生长之间的正反馈回路而不稳定。因此，一旦宏观磁流体从准平衡状态出现，它将继续稳定增长。这种模拟与生长的实验观察更具有可比性。
This is the first numerical simulation demonstrating that a macromagnetohydrodynamic (macro-MHD) mode is excited as a result of multi-scale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow based on a reduced two-fluid model. This simulation of a macro-MHD mode, a double tearing mode, is accomplished in a reversed shear equilibrium that includes zonal flow and turbulence due to kinetic ballooning modes. In the quasi-steady equilibrium, a macroscale fluctuation that has the same helicity as the double tearing mode is a part of the turbulence. After a certain period of time, the macro-MHD mode begins to grow. It effectively utilizes free energy of the equilibrium current density gradient and is destabilized by a positive feedback loop between zonal flow suppression and magnetic island growth. Thus, once the macro-MHD appears from the quasi-equilibrium, it continues to grow steadily. This simulation is more comparable with experimental observations of growin...