中文摘要：

在中国聚变工程实验堆（China Fusion Engineering Test Reactor, CFETR）的工程概念设计中，为探索有效降低偏滤器靶板热负荷的途径，相对于国际热核聚变实验堆（International Thermonuclear Experimental Reactor, ITER）特别增加了两个极向场线圈用于产生近年来新提出的雪花偏滤器位形。脱靶运行状态下，偏滤器靶板上的热负荷显著降低，但同时由于偏滤器温度的降低，杂质约束性能会变差，因此需要对CFETR雪花偏滤器的脱靶运行状态进行研究。基于边界等离子体物理模拟软件SOLPS （Scrape-off Layer Plasma Simulation），通过数值模拟研究了CFETR雪花偏滤器的脱靶运行状态。模拟中通过主等离子体室内的D2充气改变等离子体密度。当充气速度足够高时，CFETR雪花偏滤器实现完全脱靶，靶板上的离子流和热负荷都显著降低。但此时偏滤器区域等离子体温度已经非常低，杂质将容易通过X点进入芯部，有产生辐射不稳定性的风险。因此，对于CFETR雪花偏滤器较为合适的工作状态应当是部分脱靶运行。

英文摘要：

Background：In the conceptual design of China Fusion Engineering Test Reactor （CFETR）, two additional poloidal coils, with respect to International Thermonuclear Experimental Reactor （ITER）, are used to generate snowflake divertor configuration proposed recently for the purpose of exploring effective way for reducing heat loads onto divertor targets. Heat flux onto divertor targets was dramatically reduced in detached regime, while the performance of impurity screening would also be reduced due to the decrease of divertor temperature.Purpose： This study aims to simulate the detachment operation of snowflake divertor for CFETR.Methods：The detachment operational status was investigated by numerical simulation based on the edge plasma simulation software SOLPS （Scrape-off Layer Plasma Simulation）. A D2 gas puffing in the main chamber was used to change plasma density. Results：When the gas puffing rate was sufficiently high, snowflake divertor of CFETR was completely detached, and the ion flux and heat loads onto the targets significantly decreased. However, the plasma temperature in the divertor region was too low and the impurities could easily pass through the X-point to core plasma, which implied a risk of radiation instability.Conclusion：Therefore, a proper operational status for the snowflake divertor in CFETR should be partial detachment.