Sustained edge-localized-modes suppression and radiative divertor with an impurity-driven instability in tokamak plasmas
Y. Ye, Guosheng Xu, Y.Q. Tao, R. Chen, Liang Wang, Huan Guo, Huiqian Wang, Kedong Li, L.Y. Meng, Qingquan Yang, Yifeng Wang, Xin Lin, Zhen Sun, Kai Wu, Qiping Yuan, J.C. Xu, Yanmin Duan, Ling Zhang, Haiqing Liu, Baonian Wan
Abstract
We report simultaneous control of the large edge localized modes (ELMs) and divertor heat fluxes in a metal wall environment is a critical issue for steady-state operation of a tokamak fusion reactors. Here we report a sustained ELM suppression scenario achieved in the EAST tokamak compatible with radiative divertor using different seeding impurity species over a wide range of conditions. A low-n mode appears, as manifested by the oscillations of a radiation front near the X-point. This mode appears to drive strong particle transport and tungsten exhaust, which is essential to the maintenance of the ELM-stable state. We have developed a model to explain the mode excitation, by coupling the impurity radiative condensation instability to drift waves, which could explain some characteristics of the low-n mode well. The low-n mode may offer a new ELM-stable scenario compatible with radiative divertor for future fusion reactors.