To demonstrate the performance of tungsten (W) as the divertor target material and to solve the power handling problem during high power long-pulse discharge, the upgrade of EAST lower divertor is planned. In this work, the physical design of the W divertor is presented by using 2D edge plasma code SOLPS and Monte Carlo impurity transport code DIVIMP. The optimized divertor geometry is proposed after systematic examination of target shapes, target slant angles and the pump opening locations. The performance of the designed divertor is further assessed by impurity seeding. By comparing the medium and high power discharges with argon (Ar) seeding, the differences on the divertor power radiation and impurity core accumulation are distinguished. The simulated effective ion charge Z _eff fits well the scaling law, which is based on multi-machine database. Ar seeding and neon (Ne) seeding scans are carried out separately. The simulation results indicate Ar has higher power radiation efficiency than that of Ne, thus promoting the achievement of plasma detachment. However, the core compatibility with Ar is worse than with Ne. The W target erosion and W impurity transport during impurity seeding are simulated by the DIVIMP–SOLPS coupled modeling. It illustrates that under the similar divertor plasma conditions, Ar seeding causes more serious W erosion and more severe core contamination by W impurity, than Ne seeding. Finally, the divertor in–out asymmetry is studied by considering electromagnetic drifts. The simulation results manifest that the designed open vertical inner target reduces in–out asymmetry due to that its weak power radiation capability is offset by the ion flow driven by the drifts. In addition, the designed divertor is compatible with the quasi snowflake magnetic configuration. These studies will improve the understanding of W target sputtering and W impurity transport control during the radiative divertor discharges for CFETR/DEMO.

为了展示钨（W）作为偏滤器靶材的性能并解决高功率长脉冲放电过程中的功率处理问题，EAST下偏滤器的升级计划。在这项工作中，W 偏滤器的物理设计是通过使用二维边缘等离子体代码 SOLPS 和蒙特卡罗杂质传输代码 DIVIMP 来呈现的。在对目标形状、目标倾斜角和泵开口位置进行系统检查后，提出了优化的偏滤器几何形状。设计的偏滤器的性能通过杂质播种进一步评估。通过比较中高功率放电与氩（Ar）晶种，可以区分偏滤器功率辐射和杂质核心积累的差异。模拟有效离子电荷Z _eff很好地拟合了基于多机数据库的缩放律。Ar 播种和氖 (Ne) 播种扫描是分开进行的。模拟结果表明Ar比Ne具有更高的功率辐射效率，从而促进了等离子体脱离的实现。然而，与Ar的核心兼容性比与Ne差。通过DIVIMP-SOLPS耦合建模来模拟杂质播种期间的W靶侵蚀和W杂质传输。这说明在类似的偏滤器等离子体条件下，与 Ne 晶种相比，Ar 晶种会导致更严重的 W 侵蚀和 W 杂质引起的更严重的核心污染。最后，通过考虑电磁漂移来研究偏滤器进出不对称性。仿真结果表明，设计的开放式垂直内靶由于其微弱的功率辐射能力被漂移驱动的离子流所抵消，从而减少了进出不对称性。此外，设计的偏滤器与准雪花磁性配置兼容。这些研究将提高对 CFETR/DEMO 辐射偏滤器放电过程中 W 靶溅射和 W 杂质传输控制的理解。