Stationary high-performance grassy ELM regime in EAST
Stationary high-performance grassy ELM regime in EAST
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DOI：
10.1088/1741-4326/ab8e0f
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发表时间：
2020-04
期刊：
影响因子：
3.3
通讯作者：
Q.Q. Yang;G.S. Xu;N. Yan;Y.F. Wang;X. Lin;Y. Ye;G. Hu;L. Zhang;Y. Duan;J.C. Xu
中科院分区：
文献类型：
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作者：
Q.Q. Yang;G.S. Xu;N. Yan;Y.F. Wang;X. Lin;Y. Ye;G. Hu;L. Zhang;Y. Duan;J.C. Xu
自2016年活动以来，EAST托卡马克已成功获得了一个固定的高性能草状边缘局部模式（ELM）制度。通过增加加热功率或q95来增加β p都被发现有助于更高的草化榆树频率。极端紫外辐射的边缘测量结果表明，草本植物对极端紫外辐射的影响主要集中在基台区域，其对极端紫外辐射的影响比Ⅰ型植物小90%。参数扫描结果表明，草ELM区具有良好的密度控制能力，进入草ELM区与环向场方向和低杂波功率无关。统计分析表明，当边缘安全因子q95和极向β p同时足够高（q95 ≥ 5.3和β p ≥ 1.2）时，草状ELM状态在很宽的参数空间内具有很高的重现性。高三角形度δ有助于草ELM频率的提高，而EAST中没有发现JET托卡马克对草ELM高内电感li的要求。EAST草状ELM在基座顶部碰撞性中的操作空间在ν e，ped = 1 − 6的范围内。向低ve，pede方向的探索主要受到可用加热功率的限制。在基座顶部的相干模式的演变表明，草ELMs最有可能产生在陡峭的梯度区域的基座，而不是在基座顶部或附近的分界线。草ELM制度提供了一个非常有前途的方法，为进一步探索长脉冲高性能的H模式操作在EAST，与潜在的应用中国聚变工程试验堆（CFETR）作为基线方案和ELM控制的主要解决方案。
A stationary, high-performance grassy edge-localized mode (ELM) regime has been successfully accessed on the EAST tokamak since the 2016 campaign. βp increase via increase of heating power or q95 are both found to facilitate a higher grassy ELM frequency. Edge measurement of absolute extreme ultraviolet radiation indicates that the affected area by grassy ELMs is localized at the pedestal region and the perturbations there induced by grassy ELMs can be 90% smaller than that by type-I ELMs. Parameter scan demonstrates that the grassy ELM regime has good density control capacity, and the access to the grassy ELM regime is independent of the toroidal field direction and low-hybrid-wave power. Statistical analysis indicates that the grassy ELM regime is highly reproducible in a wide parameter space when edge safety factor q95 and poloidal beta βp are simultaneously high enough ( q95 ⩾ 5.3 and βp⩾1.2). High triangularity δ contributes to the increase of grassy ELM frequency while the requirement on high internal inductance li in the JET tokamak for grassy ELMs cannot be found in EAST. The operational space in pedestal top collisionality for the EAST grassy ELMs is in the range of νe,ped∗∼1−6. The exploration towards lower νe,ped∗ is mainly limited by the available heating power. Evolution of a coherent mode at pedestal top suggests that grassy ELMs most likely generate in the steep-gradient region of the pedestal, rather than on the pedestal top or near the separatrix. The grassy ELM regime offers a highly promising approach for further exploration of long-pulse high-performance H-mode operations in EAST, with potential application to the Chinese Fusion Engineering Test Reactor (CFETR) as the baseline scenario and a primary solution for the control of ELMs.