CFETR雪花偏滤器位形热流分析

The snowflake divertor which is characterized by a second order null-point will provide a new approach to reduce the high-power load on the divertor targets of the Chinese Fusion Engineering Testing Reactor(CFETR). It has two derived stable configurations, a snowflake-plus(SF+) configuration has a secondary X-point, x2, which is located in the private flux region and a snowflake-minus(SF-) configuration whose x2 is situated in the scrap-off-layer (SOL). Because the SOLPS program cannot calculate the area containing the x2, the analyses of the heat flux on the divertor targets for CFETR SF configurations tend to focus on the SF+ configuration, and the study of the SF- configuration is not sufficient. This project will mainly study the SF- configuration, carrying out the analysis of relationships between the position of the x2 and the heat flux distribution on the targets and the analysis of the phenomena of the transport in the vicinity of the x2 by using EMC3-EIRENE. Through the calculation of the peak heat flux and heat deposition width, SF configurations will be optimized. Then, according to the optimized SF configuration, the poloidal field (PF) coil will be performed initial optimizations. This research is of great significance to reduce the heat load on the targets of CFETR，which will be conducive to realize the steady state operation. It will also provide important physical support for the engineering design of the PF coil.

具有二阶零点的雪花偏滤器（SFD）平衡位形为降低中国聚变工程实验堆(CFETR)靶板高热负荷提供了新的途径。其两种稳定的衍生结构分别为第二X点，x2，位于私有通量区的SF-plus（SF+）位形和x2位于刮削层的SF-minus（SF-）位形。因SOLPS程序不能计算包含x2的区域，目前针对CFETR的SF位形的研究多集中于SF+位形，对SF-位形的研究并不深入。本项目将主要针对SF-位形，运用EMC3-EIRENE等程序系统地开展偏滤器区域的热流分析，研究x2位置与靶板热流分布的依赖关系及x2附近的输运现象；通过对靶板峰值热流和热沉积宽度的计算，获得优化的SF位形，为极向场（PF）线圈的工程设计提供重要的物理支持。该研究对降低CFETR偏滤器靶板热负载，实现稳态运行和相关工程设计具有重要意义。

具有附加零点的先进偏滤器位形为中国工程聚变实验堆（CFETR）降低偏滤器靶板的高热负荷提供了新的途径。基于0维参数，使用TEQ程序构建了一系列拉长比2.0，具有不同三角度的平衡位形。通过与偏滤器和包层的迭代，优化了包括X点在内的等离子体形状，继而获得了优化的单零（SND）位形。除了标准的SND位形，还构建了不同等离子体电流的QSF+和XD位形。计算结果显示PF线圈系统不足以维持14MA的先进位形。接着，对14MA的SND位形的放电波形（包括爬升、平顶和下降段）进行了计算。偏滤器靶板的热流由TECXY程序计算获得。结果显示QSF+位形显著降低了外靶板上的热流负载。本项目对降低CFETR热流负载具有重要的意义，有利于其实现稳态运行；也将对PF线圈的工程设计提供重要支持。