Predicting radiation damage in beryllium

Displacement damage in beryllium was predicted as a function of temperature and energy using molecular dynamics simulations. A key aim of this study was to determine if average results from large displacement cascades correspond to values predicted by the Kinchin–Pease (K–P) model. The number of residual defects remaining after 1 ps increased linearly with primary knock-on atom (PKA) energy from 0.5 keV to 2.5 keV, while the extent of residual damage was largely temperature independent from 300 K to 1100 K. The same simulation model was used to predict the directionally averaged probability of displacement as a function of displacement energy, P(EPKA), and thereby the threshold displacement energy at which the probability for displacement is 100%, Ed1.0=105 eV. There is an excellent correspondence between the K–P prediction using Ed=Ed1.0 and the number of residual defects remaining after the initial recovery phase. Also, by utilising P(EPKA), a modification to the K–P model is proposed that gives rise to an average model prediction when EPKA<2Ed1.0.

本研究通过分子动力学模拟（molecular dynamics simulations），预测了铍材料中的位移损伤随温度与入射能量的变化规律。本研究的核心目标之一，是验证大尺寸位移级联的平均结果是否与金钦-皮斯（Kinchin–Pease, K-P）模型的预测值相符。在0.5 keV至2.5 keV的能量区间内，1 ps后残余缺陷的数量随初级反冲原子（primary knock-on atom, PKA）能量的升高呈线性增长；而在300 K至1100 K的温度范围内，残余损伤的程度基本与温度无关。本研究采用同一模拟模型，预测了位移概率随位移能量变化的方向平均概率P(EPKA)，并由此得到位移概率为100%的位移阈能Ed1.0=105 eV。采用Ed=Ed1.0的K-P模型预测结果，与初始恢复阶段后残余缺陷的数量之间存在极佳的吻合度。此外，本研究借助P(EPKA)对K-P模型提出修正方案，当EPKA<2Ed1.0时，该修正模型可给出平均化的预测结果。