Extension of ELM suppression window using RMPs in EAST

Nuclear Fushion

article

P. Xie¹  Y. Sun¹  Q. Ma¹  S. Gu³  Y.Q. Liu⁴  M. Jia¹  A. Loarte⁵  X. Wu¹  Y. Chang²  T. Jia¹  T. Zhang¹  Z. Zhou¹  Q. Zang¹  B. Lyu¹  S. Fu¹  H. Sheng²  C. Ye¹  H. Yang¹  H.H. Wang¹ 

[1] Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences;University of Science and Technology of China;Oak Ridge Associated Universities;General Atomics;ITER Organization

关键词: ELM suppression;    RMPs;    tokamak;    linear plasma response;   

DOI  :  10.1088/1741-4326/aceb07

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Theq ₉₅ window for Type-I edge localized modes (ELMs) suppression usingn  = 4 even parity resonant magnetic perturbations (RMPs) has been significantly expanded to the ranges [3.9, 4.1] and [4.2, 4.8] in EAST while maintaining good confinement, which is demonstrated to be reliable and repeatable over the last two years. This window is significantly wider than the previous one achieved usingn  = 4 odd parity RMPs, which is around q_{95} = 3.7pm0.1 . Here,nrepresents the toroidal mode number of the applied RMPs andq ₉₅ is the safety factor at 95%of the normalized poloidal magnetic flux. During ELM suppression, there is only a slight drop in the plasma stored energy and density ({leqslant}10% ). The comparison of changes in the pedestal profiles suggests that ELM suppression is achieved when the pedestal gradient is kept lower than a threshold. This wideq ₉₅ window for ELM suppression is consistent with the prediction made by MARS-F modeling prior to the experiment, which located it at one of the resonantq ₉₅ windows for plasma response. The Chirikov parameter taking into account plasma response near the pedestal top, which measures plasma edge stochasticity, significantly increases whenq ₉₅ exceeds 4, mainly due to the denser neighboring rational surfaces. The modeling of plasma response reveals a strong coupling between resonant and non-resonant components across the pedestal region, which is a characteristic of the kink-peeling like response observed during RMP-ELM suppression in previous studies on EAST. These promising results demonstrate the reliability of ELM suppression using then  = 4 RMPs in EAST and expand the physical understanding on ELM suppression mechanism.

【 授权许可】

Unknown