Simulation study of hysteresis in the gradient-flux relation in toroidal plasma turbulence
Simulation study of hysteresis in the gradient-flux relation in toroidal plasma turbulence
复制标题
环形等离子体湍流梯度-通量关系滞后现象的模拟研究
DOI：
10.1088/0741-3335/57/4/044010
复制
发表时间：
2015
影响因子：
2.2
通讯作者：
and S.-I. Itoh
中科院分区：
文献类型：
--
作者：
N. Kasuya;S. Sugita;S. Inagaki;K. Itoh;M. Yagi;and S.-I. Itoh
利用热调制效应对环形等离子体中的湍流输运机制进行了全局非线性模拟。在漂移交换模式的湍流模拟中，发现热调制的快速传播和梯度通量关系的滞后。一个整体模式被非线性地激发，并且与雷诺应力的非线性耦合需要有限的持续时间来进行能量的自洽重新分配。该模式也有一个跷跷板效应：在一个位置的整体模式的振幅的增加影响在另一个径向位置的湍流不是通过诱导径向通量本身，但通过吸收能量的微观模式。微观模式的连续激发导致通量变化的加速传播，就像调制开始后的湍流传播一样。由于这些非扩散过程，滞后出现在梯度流量关系，这是与实验相比。
Global nonlinear simulations with heat modulation are carried out to understand the turbulent transport mechanism in toroidal plasmas. Rapid propagation of the heat modulation and a hysteresis in the gradient-flux relation are found in the turbulent simulation of drift-interchange modes. A global mode is excited nonlinearly, and the nonlinear couplings with Reynolds stress take a finite temporal duration for self-consistent redistribution of the energy. The mode also has a seesaw effect: increase of the amplitude of the global mode at one position affects the turbulence at the other radial position not by inducing the radial flux by itself, but by absorbing the energy from microscopic modes. Successive excitations of microscopic modes cause the accelerated propagation of the flux change like turbulence spreading after the onset of modulation. Owing to these non-diffusive processes, the hysteresis appears in the gradient-flux relation, which is compared with experiments.