EAST钨偏滤器条件下H模脱靶及其长脉冲维持的物理机制研究

Divertor detachment can provide simultaneous control of heat flux and erosion at the divertor target, and is thus essential for future steady-state fusion reactors. EAST is presently the world’s only fusion research device that is capable of long pulse operation in an ITER-relevant metal environment. This proposal leverages EAST’s unique capability, focuses on the study of detachment physics and the impact of various current drive and heating schemes on divertor detachment and control in high performance (H-mode) plasmas with the tungsten divertor. In addition, this proposal will investigate, for the first time, the effects of and the interplay between divertor closure and cross-field drifts on divertor detachment. By addressing these critical physics issues, the proposed research aims to further optimize detachment performance in H-modes, and find appropriate detachment schemes compatible with high performance H-mode plasmas. This proposed research will not only provide an important physics basis for EAST steady-state operation, but also have significant implications for divertor power dissipation in future fusion devices, such as ITER and CFETR.

等离子体脱靶可以有效降低偏滤器靶板表面的热沉积和腐蚀，为聚变反应提供了一种极具前景的运行状态。EAST是目前唯一有能力开展和ITER相关的金属壁环境下稳态运行的聚变研究装置。本项目将紧紧围绕EAST稳态运行的迫切需要，针对钨偏滤器条件下H模脱靶的相关前沿物理问题，重点开展粒子漂移、偏滤器封闭性对H模脱靶的影响及其物理机制的研究，同时率先针对偏滤器封闭性和粒子漂移间相互协同作用开展研究。此外，研究射频波、中性束等不同加热模式对偏滤器脱靶的影响。进一步优化偏滤器性能，探寻适于长脉冲维持的H模脱靶运行模式。该研究计划不仅为EAST稳态运行打下一个重要的物理基础，也为ITER、CFETR以及未来磁约束聚变堆缓解靶板热流提供数据支持和参考依据。

等离子体脱靶可以有效降低偏滤器靶板表面的热沉积和材料腐蚀，是国际上普遍认可的未来聚变堆最有前景的偏滤器运行状态。依托EAST超导托卡马克，在钨偏滤器条件下，系统开展了偏滤器脱靶实验研究，实现了EAST高约束模式脱靶和约束性能的有效兼容。实验分析了影响偏滤器脱靶的主要因素，发现边界漂移容易引起偏滤器粒子和热输运的改变，进而影响内外偏滤器脱靶。利用新型下钨偏滤器，发现更为封闭的偏滤器有助于降低偏滤器脱靶密度阈值，提升主等离子体约束性能。进一步理解了偏滤器封闭性及其边界漂移对偏滤器脱靶影响的协同效应，优化偏滤器放电位形，一定程度提升了偏滤器杂质屏蔽和粒子排除，利用极少量杂质注入和快速响应的方法，在有效降低偏滤器靶板热流及温度的同时，获得了大于20s的稳定H模脱靶运行。实验和模拟研究表面，加热功率与脱靶阈值存在线性依赖关系，特别是射频波加热，提升了等离子体电子温度，进而影响偏滤器脱靶行为。此外，在EAST上也实现了氦等离子体脱靶，但其脱靶阈值明显高于氘等离子体。这些结果为未来EAST实现高性能长脉冲稳态运行，以及偏滤器升级优化提供参考依据。