电阻气球不稳定性层流区的伪混沌极向输运
Pseudochaotic poloidal transport in the laminar regime of the resistive ballooning instabilities
摘要：
在环形几何中，在建立充分发展的湍流状态之前，观察到压力梯度驱动的湍流的所谓拓扑不稳定性。在这种中间状态下，窄谱带的模式占主导地位的动态，从而导致形成的电势的等值面与复杂的拓扑结构。由于示踪粒子的E x B平流沿着这些等值面发生，它们的拓扑复杂性显著影响径向和极向输送的特征。特别是，它们都变得非常非扩散和非高斯。由于径向运输决定了系统的限制性能和极向运输控制的平衡动力学（在任何磁性表面），在两个方向上的非扩散模型的发展，因此物理利益。在以前的工作中，作者构造了一个描述径向输运的分数阶模型。在这方面的贡献，最近的结果周期分数模型利用建设一个有效的极向运输模型。数值计算使用一个三维减少磁流体动力学方程组的分数周期模型的解析解进行了比较。结果表明，上述解析解准确地描述极向输运，这原来是超扩散与指数$α=1$。
英文摘要：
In toroidal geometry, and prior to the establishment of a fully developed turbulent state, the so-called topological instability of the pressure-gradient-driven turbulence is observed. In this intermediate state, a narrow spectral band of modes dominates the dynamics, giving rise to the formation of iso-surfaces of electric potential with a complicated topology. Since E x B advection of tracer particles takes place along these iso-surfaces, their topological complexity affects the characteristic features of radial and poloidal transport dramatically. In particular, they both become strongly non-diffusive and non-Gaussian. Since radial transport determines the system confinement properties and poloidal transport controls the equilibration dynamics (on any magnetic surface), the development of non-diffusive models in both directions is thus of physical interest. In previous work, a fractional model to describe radial transport was constructed by the authors. In this contribution, recent results on periodic fractional models are exploited for the construction of an effective model of poloidal transport. Numerical computations using a three-dimensional reduced magnetohydrodynamic set of equations are compared with analytical solutions of the fractional periodic model. It is shown that the aforementioned analytical solutions accurately describe poloidal transport, which turns out to be superdiffusive with index $α=1$.
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