Rotation braking with n = 1 nonaxisymmetric magnetic perturbation in the EAST tokamak

The toroidal plasma rotation braking effect during the application of n = 1 static resonant magnetic perturbation is studied by momentum transport analysis in the EAST tokamak. The braking torque shows a global profile and two peaks located near the plasma core and the edge, respectively. The effect of momentum diffusion contributes significantly to the calculated torque. Simulation results with the obtained torque and momentum diffusion coefficients well reproduce the observed plasma rotation evolution. Neoclassical toroidal viscosity (NTV) torque is modeled for comparison with the experimental torque. The total integrated NTV torque is around −0.12 Nm, which is comparable to the observed braking torque (around −0.33 Nm). In the plasma edge, there is a peak in the NTV torque profile, which agrees well in amplitude with the obvious peak in the observed torque density profile. An additional peak in the NTV torque profile due to the ion bounce resonance is also located in the core region. However, the magnitude of this peak is much smaller than the observed one near the plasma core.

本研究基于EAST托卡马克装置，通过动量输运分析，探究了施加n=1静态共振磁扰动时的环向等离子体旋转制动效应。制动力矩呈现整体分布特征，且分别在等离子体芯部与边缘区域存在两个峰值。动量扩散效应对计算所得的力矩具有显著贡献。基于获取的力矩与动量扩散系数开展的模拟结果，良好复现了观测到的等离子体旋转演化过程。为与实验力矩进行对比，本研究对新经典环向粘滞（Neoclassical Toroidal Viscosity, NTV）力矩进行了建模。总积分NTV力矩约为-0.12牛·米，与观测到的制动力矩（约-0.33牛·米）量级相当。在等离子体边缘区域，NTV力矩分布存在一个峰值，其幅值与观测到的力矩密度分布中的显著峰值吻合良好。此外，由离子弹跳共振引发的NTV力矩分布额外峰值也位于芯部区域，但该峰值的幅值远小于等离子体芯部附近观测到的峰值。