Topological bifurcation of helical flows in magnetized plasmas with density gradient and parallel flow shear
Topological bifurcation of helical flows in magnetized plasmas with density gradient and parallel flow shear
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DOI：
10.1063/1.5000343
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发表时间：
2017-11
影响因子：
2.2
通讯作者：
M. Sasaki;N. Kasuya;K. Itoh;S. Toda;T. Yamada;Y. Kosuga;Y. Nagashima;Tatsuya Kobayashi;H. Arakawa;K. Yamasaki;A. Fujisawa;S. Inagaki;S. Itoh
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作者：
M. Sasaki;N. Kasuya;K. Itoh;S. Toda;T. Yamada;Y. Kosuga;Y. Nagashima;Tatsuya Kobayashi;H. Arakawa;K. Yamasaki;A. Fujisawa;S. Inagaki;S. Itoh
通过湍流模拟，证明了非平衡磁化等离子体中流动的拓扑分岔。一个系统的两个通用的湍流源，密度梯度和平行流，被认为是。为了表征流型的手征性，引入了流型的拓扑指数。我们在这里报告的顺磁驱动流形成的结构，具有相反的手征同轴螺旋。通过改变等离子体粒子的来源，改变密度梯度，得到三个湍流状态之间的过渡。除了漂移波和D'Angelo模主导的两个湍流态外，还发现了一个新的态，在这个新的态中，两个自由能源同时驱动涨落，并与其它自由能源竞争.结果表明了非平衡磁化等离子体中湍流产生的一般特征。
The topological bifurcation of the flow in non-equilibrium magnetized plasmas is demonstrated by a turbulence simulation. A system with two generic sources of turbulence, the gradients of density and parallel flow, is considered. Topological index of the flow is introduced, in order to indicate the chirality of flow pattern. We here report that the turbulence-driven flow forms the structure of co-axial helixes with opposite chirality. By changing the source of plasma particles, which modifies the density gradient, the transition between three turbulent states is obtained. In addition to the two turbulent states, which are dominated by the drift wave and the D'Angelo mode, respectively, the new state is found. In this third state, fluctuations are driven by both of the free energy sources simultaneously, and compete with the others. The result illustrates the generic feature of turbulence flow generation in non-equilibrium magnetized plasmas.