预置离位损伤对钨中氘滞留与起泡行为规律的影响研究

High-flux plasma exposure and high-energy neutron irradiation are the critical issues the plasma-facing materials (PFM) will face in the Tokamak. With excellent thermaldynamic properties, tungsten has been considered as the most promising candidate of PFM. Since then, synegistic effect of neutron irradiation and plasma exposure in tungsten has been one of research hot spots in the fusion materials area. Tritium retention and hydrogen-induced surface blistering became the main concerns that may affect the PFM’s service properties and operation stability of the reactor. In this program, heavy ion implantation will be used as a surrogate of neutron irradiation to produce displacement damage in tungsten. Based on EAST device and linear plasma generator STEP, deuterium behaviors in tungsten with numerous displacement damage will be investigated via making use of reliable and advanced instruments, such as NRA, SEM, TDS, TMAP etc. The object is to gain a more sophisticated insight into the role that displacement damage played in deuterium transport, retention and blistering. A transport model which will help predict the deuterium retention and surface blistering in damaged tungsten is expected. With the development of this project, important references will be offered to the evaluation of PFM’s service properties and lifetime.

大束流等离子体和高能中子辐照是托卡马克面对等离子体材料（PFM）将面临的挑战。自热力学性能优异的钨被视为最有前途的PFM以来，钨的等离子体辐照和中子辐照效应就成为PFM材料的研究热点，氚滞留与表面起泡等关系到PFM服役性能和装置稳定运行的问题得到广泛关注。本项目将针对中子辐照缺陷如何影响氘滞留与表面起泡行为这一方向开展研究，利用重离子辐照预置与中子辐照相似的离位损伤，基于EAST大装置和直线等离子体装置STEP开展多组低能大束流等离子体辐照实验，结合核反应分析、扫描电子显微镜、热脱附谱等先进测试技术，从缺陷密度和损伤深度双维度研究损伤缺陷对钨中氘分布、滞留以及聚集等过程的具体影响；结合速率理论方法，阐明离位损伤对钨中氘输运和聚集成泡过程的影响机理；加深对离位损伤下钨中氘滞留与起泡行为的理解，尝试建立离位损伤对氘滞留与起泡过程的影响模型，为未来PFM服役性能和使用寿命评估提供重要参考。

大束流氘氚等离子体辐照和个中子辐照是托卡马克装置面对等离子体材料（PFMs）将面临的主要挑战；氘氚滞留与表面起泡行为关系到PFMs服役性能与寿命和装置运行的稳定性与安全性。本项目针对PFMs候选材料——金属钨，利用重离子辐照预置与中子辐照相似的离位损伤，结合正电子湮没、核反应分析、扫描电子显微镜、热脱附谱等先进技术，开展大量实验，从缺陷密度、损伤深度、辐照条件、材料组织状态等维度，分析预置离位损伤对钨中氘滞留与起泡行为规律的具体影响。研究结果表明，预置离位损伤对钨表面氘聚集行为与总滞留均有显著的影响，且该影响随预置损伤缺陷的增多而增大。首先，预置离位损伤极大地抑制钨表面晶粒内部的氘聚集起泡，这种抑制效应在高温离子损伤钨中有恢复的迹象。另外，氘滞留结果显示，预置离位损伤不仅为氘滞留提供了更多的捕获位，同时其对氘聚集成泡行为的影响也间接导致了钨体内氘滞留的增多。这种氘滞留增强效应随损伤深度的增加而更加明显。预置离位损伤对钨中氘聚集成泡的抑制作用与氘输运滞留的增强效应广泛存在于各类组织结构的钨材料中。因此，中子辐照损伤条件将显著抑制钨基PFMs材料的氢致表面起泡现象，但会带来较大的氢燃料滞留威胁。