Effects of neoclassical toroidal viscosity on plasma flow evolution in the presence of resonant magnetic perturbation in a tokamak

TL;DR

This paper investigates how neoclassical toroidal viscosity influences plasma flow and mode locking in tokamaks with resonant magnetic perturbations, revealing its localized effects and interaction with electromagnetic torque.

Contribution

It provides a cylindrical theory model analysis showing NTV's limited effect on resonant surface flow but significant impact on core plasma rotation and torque interactions.

Findings

NTV has minimal effect on flow at the resonant surface.

NTV reduces core plasma flows slightly with uniform pressure.

Elevated beta enhances NTV torque but suppresses electromagnetic torque.

Abstract

Effects of neoclassical toroidal viscosity (NTV) on plasma flow evolution in the presence of resonant magnetic perturbation (RMP) in a tokamak have been evaluated using a cylindrical theory model. Calculations show that the introduction of NTV has almost no effect on the flow on the resonant surface, so the locked or unlocked state on the resonant surface remains unchanged, but it impacts the rotation profile in the core region. The toroidal, poloidal, and parallel flows in the core region are slightly reduced with uniform pressure. For non-uniform pressure profiles, elevated $\beta$ enhances the global amplitude of NTV torque but suppresses that of electromagnetic (EM) torque. These two driving terms collectively maintain the locked mode state.