Gyrokinetic simulations of the effects of magnetic islands on microturbulence in KSTAR

TL;DR

This study uses gyrokinetic simulations to analyze how magnetic islands influence ion temperature gradient turbulence and transport in the KSTAR tokamak, revealing enhanced turbulence and transport near X-points with good experimental agreement.

Contribution

It provides the first detailed gyrokinetic simulation analysis of magnetic island effects on microturbulence in KSTAR, including anisotropic fluctuation structures and transport variations.

Findings

Magnetic islands significantly increase turbulent particle and heat transport.

Transport varies toroidally, with enhancement near the island X-point.

Simulations agree quantitatively with KSTAR experimental spectra.

Abstract

Gyrokinetic simulations are utilized to study effects of magnetic islands on the ion temperature gradient (ITG) turbulence in the KSTAR tokamak with resonant magnetic perturbations. Simulations show that the transport is controlled by the nonlinear interactions between the ITG turbulence and self-generated vortex flows and zonal flows, leading to an anisotropic structure of fluctuation and transport on the poloidal plane and in the toroidal direction. Magnetic islands greatly enhance turbulent transport of both particle and heat. The turbulent transport exhibits variations in the toroidal direction, with transport through the resonant layer near the island X-point being enhanced when the X-point is located at the outer mid-plane. A quantitative agreement is shown between simulations and KSTAR experiments in terms of time frequency and perpendicular wavevector spectrum.