Molecular Dynamics Simulation of Diffusion Behavior of Self-Interstitial Atoms Cluster in Tungsten

Tungsten is considered as the most potential plasma-facing material in the future fusion reactor. However, in the real environment of future fusion reactor, 14 MeV high-energy neutron irradiation produced by deuterium-tritium fusion reaction will cause serious atoms displacement and various defects accumulation in materials. Here, self-interstitial atom and its clusters are the most common defects in neutron irradiation damage situation, so it is of great significance to study the aggregation and diffusion behavior of interstitial clusters. Molecular dynamics simulation is used to study the stable structures and formation energies of 1/2<111> and <100> self-interstitial atom clusters in tungsten, the diffusion behavior of 1/2<111> self-interstitial atom clusters with different sizes was also studied. The results will provide accurate and complete input parameters for larger-scale simulations such as Kinetic Monte Carlo and cluster dynamics, and provide the basis for correctly understanding and evaluating the neutron irradiation behavior in tungsten.

钨被认为是未来聚变堆中最具潜力的面向等离子体材料（plasma-facing material）。然而，在未来聚变堆的真实服役环境中，氘氚聚变反应产生的14 MeV高能中子辐照会在材料中引发严重的原子位移与各类缺陷累积。其中，自间隙原子（self-interstitial atom）及其团簇是中子辐照损伤场景中最常见的缺陷，因此研究间隙团簇的聚集与扩散行为具有重要意义。本研究采用分子动力学模拟（Molecular dynamics simulation），研究了钨中1/2<111>与<100>型自间隙原子团簇的稳定结构及形成能，同时分析了不同尺寸的1/2<111>型自间隙原子团簇的扩散行为。研究结果将为动力学蒙特卡洛（Kinetic Monte Carlo）、团簇动力学（cluster dynamics）等更大尺度的模拟提供精准完整的输入参数，并为正确理解与评估钨中的中子辐照行为提供理论依据。