超导偏滤器托卡马克中钨杂质产生及在边界等离子体中输运的实验和模拟研究

Tungsten is currently the most promising plasma facing material to be used in future fusion reactors. However, as high atomic number material, the most serious problem is that the tungsten impurities can move into the core plasma and induce high energy loss by radiation, which will do great damage to the quality of the fusion plasma. Therefore, studies of tungsten impurities generation and their transport in devices are of an extremely important significance . Because of the great similarity between superconducting divertor Tokamaks EAST and ITER, this research proposed to build up tungsten impurity spectroscopy on EAST. The inverse photon efficiency under different plasma conditions of EAST could be obtained by the combination of experiments and simulations. The erosion of divertor tungsten and transport of tungsten impurities in edge plasma will be measured under different operation conditions. The EAST experiments will be simulated by combined codes: plasma fluid code SOLPS5.0, materials erosion and deposition code ERO and impurity transport code DIVIMP. It seeks to grasp the laws of tungsten impurities generation from EAST divertor and their transport in edge plasma via the comparison of experimental and simulation results. The erosion of ITER full tungsten divertor and impurity transport will be predicted. This research can provide scientific basis for the design and operation of ITER and future fusion devices.

钨是目前最有希望在未来聚变堆中使用的面向等离子体材料，但是作为高原子序数材料，其最大的问题是钨杂质进入中心等离子体并且产生大量的辐射能量损失，严重损害聚变等离子体的品质，因此对于聚变装置中钨杂质产生及其输运的研究有着极其重要的意义。由于超导偏滤器托卡马克EAST与ITER具有极大的相似性，本项研究拟在EAST上建立钨杂质光谱，通过实验与模拟结合的方法得到EAST在不同等离子体条件下的反光子效率，并测量不同运行条件下偏滤器钨的腐蚀和钨杂质在边界等离子体中的输运情况，结合等离子体流体程序SOLPS5.0、材料腐蚀与沉积程序ERO以及杂质输运程序DIVIMP对EAST上的实验进行模拟，通过比较实验和模拟的结果，力图掌握EAST偏滤器上钨杂质的产生和在边界等离子体中输运的规律，并对ITER全钨偏滤器的腐蚀和杂质输运进行预测，为ITER和未来的聚变装置的设计与运行提供科学基础。

钨材料具有高熔点、高热导率、低溅射率、低氚滞留量以及耐中子辐照等优良性能，已经被选用为ITER的偏滤器面向等离子体材料,但是钨杂质进入中心等离子体会产生大量的辐射能量损失，因此需要理解聚变装置中钨杂质产生及其输运的物理过程，从而找到控制中心等离子体中钨杂质水平的有效方法。EAST上偏滤器在2014年升级为全钨结构，为研究偏滤器托卡马克中钨杂质相关问题提供了重要的平台。本项目首先在EAST托卡马克上搭建了高时间和空间分辨率的钨杂质光谱诊断系统，实现了对钨杂质源的监测，系统地研究了EAST上在不同运行条件下的偏滤器钨杂质产生情况。同时利用ERO和DIVIMP程序对相关实验结果进行模拟，理解了钨的腐蚀和再沉积的主要机制，尤其是碳杂质对钨溅射的贡献，在此基础上通过局部注入气体成功抑制了钨杂质在偏滤器的产生。项目按原计划完成，也达到了预期的研究目标，研究成果对ITER以及未来的聚变堆设计和运行具有重要的参考价值。