面向等离子体材料在离子-中子协同辐照下的缺陷团簇动力学模拟

Controlled thermonuclear fusion is one of the major strategic means to solve energy and environmental problems. Radiation damages of plasma-facing materials under heat plasma irradiation will seriously restrict the stable operation and development of fusion devices. Considering the complexity of irradiation factors, difficulties in nuclear fusion experiments as well as in order to shorten the research cycle, it is very important to perform related theoretical researches on the underlying issues. Based on the fundamental physics of ions-neutron interaction with solid and the micro-mechanism of defect evolution, dynamical evolution of defects and radiation damages in plasma-facing materials under ions-neutron co-irradiation will be studied by using a multi-scale approach in this project. The multi-scale simulation program, based on SRIM software/meolcular dynamics method for radiaion damage - atomic scale simulation methods - cluster dynamics model, is developed to study the generation, reaction, diffusion and accumulation processes of defects, which can further describe the concentration distributions in time and space of defect clusters with different sizes. Finally, the quantitative analysis of the formation mechanism of damages under ions-neutron synergistic irradiations will be performed from the microscopic point of view, such as, surface erosion, D/T/He retention, H/He embrittlement and even blisters, etc. The results will directly provide theoretical support and forecast to the radiation damages of plasma-facing materials under the practical plasma conditions in fusion reactors like ITER.

受控热核聚变是解决能源和环境污染问题的重大战略手段之一，而面向等离子体材料在高温等离子体辐照下的损伤问题会严重制约其稳定运行和发展。鉴于辐照因素的复杂性，核聚变反应堆实验上的困难，以及为了缩短研究周期，对相关基础问题的理论研究至关重要。本项目将从离子、中子与固体的相互作用和缺陷演化的微观机制等基础物理出发，研究离子-中子协同辐照下，面向等离子体材料中缺陷的动力学演化过程以及辐照损伤的分布情况。拟基于SRIM软件/辐照损伤分子动力学方法-原子尺度方法-缺陷团簇动力学方法的多尺度模拟方案，定量地研究各种缺陷的产生、扩散、反应和积聚等演化过程，从而给出缺陷团簇的浓度随尺寸和时间、空间的分布。最终实现从微观角度分析面向等离子体材料的表面侵蚀、D/T/He滞留，H/He脆甚至表面起泡等损伤的形成机理。其结果将直接为ITER等离子体环境下的面向等离子体材料的辐照损伤及服役行为提供理论指导及预测。

本项目着重于探索面向等离子体材料在离子—中子协同辐照下动力学损伤问题的新理论和新方法。通过自主发展离子辐照材料初级损伤模拟的三维MC并行软件（IM3D）和深度分辨三元缺陷团簇动力学模型（IRadMat），并耦合原子尺度方法，建立了“SRIM/IM3D-DFT/MD-IRadMat”的多尺度动力学模拟框架，定量研究了离子—中子协同辐照下材料中缺陷的产生、扩散、反应和积聚等过程，获得了与实验一致的缺陷尺寸和深度分布。从微观角度探讨了高温等离子体辐照下纯钨/铍/铁核材料的表面侵蚀、D/T/He滞留、H/He脆甚至表面起泡等损伤的形成机理，建立了材料单离子辐照性能的一般理论分析方法。主要研究成果为：1）指出了粗糙表面导致的离子辐照反照率效应会加剧材料中的离子初级滞留和表面重构，但有利于降低材料的离子表面溅射；2）揭示了界面对附近点缺陷的偏置吸收与辐照级联区域点缺陷的复合间的竞争决定了纳米材料的高抗辐照性能；3）提出了钨中自间隙原子间的强相互作用导致了其团簇沿<111>方向的一维快速蠕动行为；4）率先从介观尺度指出了H-H和He-He结合能的差异决定了H/He在钨/铍中不同的滞留深度分布行为；5）建议可使用纳米晶铁基结构材料以提升其抗中子辐照性能，应使用粗晶钨基面向等离子体材料以降低其氢氦滞留；6）发表SCI学术论文10篇，申请中国软件著作权1项，做大会主题和特邀报告各1次。