Impact of Micro-Scale Stochastic Zonal Flows on the Macro-Scale Visco-Resistive Magnetohydrodynamic Modes

oleh: Sara Moradi, Anantanarayanan Thyagaraja

Format: Article
Diterbitkan: MDPI AG 2020-03-01

Deskripsi

A model is developed to simulate micro-scale turbulence driven Zonal Flows (ZFs), and their impact on the Magnetohydrodynamic (MHD) tearing and kink modes is examined. The model is based on a stochastic representation of the micro-scale ZFs with a given Alfv&#233;n Mach number, <i>M<sub>S</sub></i>. Two approaches were explored: (i) passive stochastic model where the ZFs amplitudes are independent of the MHD mode amplitude, and (ii) the semi-stochastic model where the amplitudes of the ZFs have a dependence on the amplitude of the MHD mode itself. The results show that the stochastic ZFs can significantly stabilise the (2,1) and (1,1) MHD modes even at very low kinematic viscosity, where the mode is linearly unstable. Our results therefore indicate a possible mechanism for stabilisation of the MHD modes via small-scale perturbations in poloidal flow, simulating the turbulence driven ZFs.