EAST上微量重杂质诱发新经典撕裂模的实验研究

当前托卡马克和未来的ITER及CFETR聚变装置中，新经典撕裂模的解稳及非线性增长严重限制高约束等离子体的稳态运行。多螺旋度新经典撕裂模耦合及多尺度不稳定性的作用通常触发等离子体大破裂。由于面向等离子体的装置内部关键部件都是重金属材料，在高约束等离子体中，芯部重杂质处于高电离太且总是维持一定的浓度，低浓度的重杂质影响等离子体集总不稳定性。在最近的EAST高约束等离子体运行中，利用GEM相机（Gas Electron Multiplier）观察到了铁杂质分布变化不可避免的激发新经典撕裂模（NTM），特别地，这类NTM的解稳不具有锯齿崩塌等触发事件[E. Li et al, Nucl. Fusion 59, 106030 (2019)]。本项目将结合诊断数据和理论模型，在EAST上进一步开展相关实验来研究重杂质在这类NTM解稳中的作用，为发展高效的NTM主动控制方法提供实验数据支持。

In current tokamaks and the future ITER as well as CFETR, the destabilzation and nonlinear growth of a neocalssical tearing mode (NTM) is threatening the steady state operation of high confinement plasmas. The NTMs may lead to a disruption of high performance plasmas once multiple heliciites are coupled and/or multi-scale instabilites are occuring. Since the materials facing to the plasmas are mental, the heavy impurity is highly ionized and always keeps a certain concentration in the reactor core of high-mode plasmas which tends to influence the collective instabilites. In recent EAST high performance scenario, a noval GEM camera based on gas electron multiliter detectors is used to measure the x-ray radiaitons in the direction tangential to magnetic lines, and has shown the iron profile according to the experimental cooling factor. The change of iron profiles is found related to the destabilzation of NTM, particularly without any triggering event[E. Li et al, Nucl. Fusion 59, 106030 (2019)]. It is anticipated that this phenomina would be continually investigated on EAST, with more detailed experiments in combination with advanced diagnostics and theories. This research will provide strategy to design the efficient method for NTM control.