注入杂质等离子体对钨第一壁材料表面及燃料滞留的影响机理研究

Radiative divertor by impurities seeding has been applied currently in high power long pulse operation Tokamak fusion device to avoid divertor damage by excessive heat and particle fluxes. However, the interaction between seeding impurity plasmas with first wall tungsten materials and it's influence on fuel retention are still not fully understood. In this research work, systematic research about the interaction of seeding impurity plasmas with first wall tungsten material will be performed in laboratory and compare with the result obtained from samples exposed to EAST Tokamak device. The research results can help us to understand the changes of the surface morphology, microstructure and sputtering yield of tungsten caused by the seeding impurity plasmas irradiation with different parameters, comprehend the bonding state between tungsten and seeding impurities, as well as the retention and releasing behavior of seeding impurities, and grasp the influence of seeding impurity plasmas irradiation on fuel (deuterium) retention in tungsten material. Based on these research results the physical model about the influence of seeding impurity plasmas irradiation on the surface of tungsten and fuel retention will be proposed to predict the service lifetime, failure mode and fuel retention behavior of tungsten material used in Tokamak nuclear fusion device under impurity seeding condition.

为降低托卡马克装置长脉冲、高参数运行条件下的靶板表面溅射和热沉积，注入杂质的辐射偏滤器物理方案已陆续在国内外装置上展开初步研究。但杂质注入条件下杂质与第一壁钨材料相互作用及其对燃料滞留行为的影响尚不明晰。通过在实验室条件下开展注入杂质等离子体与钨第一壁材料相互作用的系统研究，并与EAST装置搭载实验进行对比,理解不同杂质注入条件下钨材料表面形貌、微观结构和溅射产额的变化规律，掌握杂质元素在钨材料中的键合、滞留与释放行为，揭示注入杂质等离子体辐照钨第一壁材料对燃料（氘）滞留的影响。在此基础上，建立注入杂质等离子体辐照下钨材料表面及燃料滞留变化的物理模型，最终揭示杂质注入条件下托卡马克核聚变装置中钨第一壁材料的失效形式、使用寿命及燃料滞留行为。

针对托克马克装置注入杂质辐射偏滤器条件下第一壁材料服役环境，开展了实验室模拟注入杂质等离子体辐照下钨第一壁材料刻蚀及燃料滞留研究，利用直线等离子体源，考察了氮、氩、及氦掺杂氘等离子体辐照下钨材料刻蚀及燃料（氘）滞留行为；模拟装置运行环境下Li对Wu-Cu偏滤器腐蚀作用；并发展了面向核聚变能环境下服役的一种固体润滑薄膜材料。研究结果表明，氮等离子体辐照后钨表面形成氮化钨层，在高温加热作用至1073K氮化钨层开始分解，1473K完全分解为金属钨；钨中氘滞留随辐照通量的增加而增大且在考察通量内（10^26/m^2）未见饱和，钨中氘滞留随储存时间的延长而下降，一个月储存期后下降30-40%达到饱和；氮/氘混合等离子体辐照通过稀释边界等离子体降低了材料中氘滞留，同时由于表面氮化钨的形成减小了钨的刻蚀；氩/氦混合等离子体辐照在降低滞留的同时使得钨刻蚀速率明显上升；氦/氘混合等离子体辐照使得氘在钨中的滞留下降1-2个数量级。EAST装置中平面材料等离子体辐照实验揭示，钨中氘滞留与材料自身孔隙率成正比，钨中孔洞和缺陷越多，氘滞留越高。针对Wu-Cu偏滤器Cu穿管腐蚀问题，开展了模拟装置运行下利用Cu-Li-Cu多层薄膜体系不同温度热处理，考察了Li对Cu穿管腐蚀作用，结果表明热处理温度高于280℃时Cu-Li界面开始出现相互扩散，以上研究结果为EAST托卡马克穿管钨偏滤器铜管Li化后安全使用温度区间提供了实验证据。项目组针对未来核聚变堆远程操作维护系统对传动部件润滑要求，与合肥等离子体物理研究所合作，发展适用于EAST托卡马克大科学装置上的远程维护操作臂运动部件润滑材料及技术，制备的高承载、耐辐照MoS2/DLC/Ti三元复合薄膜在2016年夏季EAST远程控制机械臂运动部件润滑上获得应用，机械臂在EAST装置上试运行成功。