Abstract:

The molecular dynamics simulations of interactions between CH₃ and tungsten materials of different temperature are carried out, based on the reactive empirical band order function to understand the possible mechanisms of C, H deposition and sputtering on the first wall in fusion device. The energy of incident CH3 particle is 200eV. The simulated results show that the deposition atoms of C and H increase with incident particle increasing, when substrate temperature is 100K the deposition of C atoms was more than others temperatures’, and when the substrate temperature is 1200K, the incident is greater than 1.510¹⁶cm^-2, the deposited C atoms is less than other substrate temperatures’ deposited C atoms. CH₃ was decomposed during CH₃ bombardment with substrate, about 9% of the CH₃ was completed decomposition; about 40% of the CH₃ was decomposited to CH₂ and H; about 23% of the CH₃ was decomposited to CH and 2H. The scattering angle of C and H atoms are mainly distributed between 5° and 85°, the distribution of scattering angle maximum of C atom was 40~50° or 50~60°, the minimum distribution of C atom at between 0 and 10° or between 80° and 90°; the energy of scattered C atoms is between 0 and 140eV, more than 98% scattering atoms is between 0 and 120eV among of them, and the average scattering energy increases with the increase of substrate temperature, from 65.5eV increased to 68.5eV, The distribution maximum of H atom was 40~50°, the minimum distribution of H atom at between 0 and 10°. Scattering energy of H atom is between 0 and 140eV, but about 70% of the scattering H atomic energy within 40eV, the average scattering energy decreases with the increase of substrate temperature, from 13.92eV decreased to 13.05eV.

Key words: Molecular dynamics, Fusion materials, Deposited rate, Sputtering rate, Scattering

摘要：

采用分子动力学方法模拟200eV的CH₃粒子轰击到不同基底温度的钨样品上，分析了C、H原子在钨表面的沉积、散射

及溅射情况，结果表明C、H原子沉降量均随入射剂量的增加而增加。在基底温度为100K时，相同入射剂量下沉积的C

原子最多，而当基底温度为1200K，在入射剂量大于1.510¹⁶cm^-2时，C原子的沉降量小于其它基底温度下的C的沉降

量。CH₃在轰击样品时发生了分解，各种分解情况随基底温度变化较小，其中不同基底温度下一级分解率在40%上下

波动，二级分解在23%左右，而完全分解的CH₃在9%左右。C、H原子的散射角主要分布在5~85°间，散射C原子分布

的最大值分布在40~50°或50~60°间，散射C原子分布的最小值分布在0~10°或80~90°间；而不同基底温度下散射H原子

分布的最大值均在40~50°间，最小值均在0~10°间。散射C原子的能量在0~140eV之间，散射能量为0~120eV的C原子

占散射总量的98%以上，散射C原子平均能量随基底温度的增加而增加，其变化从65.5eV增加到68.5eV；散射H原子

的能量也在0~140eV之间，但大约70%的散射H原子能量在40eV以内，散射平均能量随基底温度的增加而减小，其变

化从13.92eV减小到13.05eV。

关键词: 分子动力学, 聚变材料, 沉积率, 溅射率, 散射