Magnetic island formation and rotation braking induced by low-Z impurity penetration in an EAST plasma

TL;DR

This study uses 3D resistive MHD simulations to investigate how low-Z impurity penetration in EAST tokamak plasmas leads to magnetic island formation and rotation braking, highlighting impurity radiation's role in tearing mode dynamics.

Contribution

The paper demonstrates, through simulations, the detailed mechanisms by which low-Z impurities influence magnetic island behavior and mode damping in EAST plasmas, providing new insights into impurity effects.

Findings

Formation of multiple magnetic islands during impurity penetration

Impurity radiation enhances parallel current perturbations

Impurity accumulation dampens 2=1 island rotation

Abstract

Recent observations of the successive formations of the 4=1; 3=1, and 2=1 magnetic islands as well as the subsequent braking of the 2=1 mode during a low-Z impurity penetration process in EAST experiments are well reproduced in our 3D resistive MHD simulations. The enhanced parallel current perturbation induced by impurity radiation predominately contributes to the tearing mode growth, and the 2=1 island rotation is mainly damped by the impurity accumulation as results of the influence from high n modes.