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使用分子动力学方法模拟了低能H原子与碳氢薄膜的作用过程,以了解基于核聚变装置中等离子体与C基材料的相互作用机制。模拟中使用REBO(reactive empirical bond order)势函数来描述C-H体系中原子间的相互作用,并使用Berendsen热浴来控制体系的温度。文中着重探讨了入射能量对低能H原子刻蚀碳氢薄膜的影响,入射能量分别为0.3,1,5和10eV。模拟结果显示随着入射能量的增加,H原子的吸附率增加,C原子和H原子的刻蚀率增加。同一能量下H原子比C原子更易发生刻蚀。通过讨论发现在H原子与碳氢薄膜作用过程中,当能量大于1 eV时,由于入射的H原子先沉积在表面并与表面原子发生反应形成碳氢化合物,然后在后续入射粒子的轰击下碳氢化合物在表面发生解吸附现象,从而导致了C原子的刻蚀,因此C原子的刻蚀发生主要是化学增强的物理溅射。
Molecular dynamics simulation was used to simulate the interaction between low-energy H atoms and hydrocarbon films to understand the interaction mechanism between plasma and C-based materials in nuclear fusion devices. REBO (reactive empirical bond order) potential function is used in the simulation to describe the interaction between atoms in the C-H system, and the Berendsen thermal bath is used to control the temperature of the system. In this paper, the influence of incident energy on low-energy H-atom etching of thin films of hydrogen is mainly discussed. The incident energies are 0.3, 1, 5 and 10eV respectively. The simulation results show that with the increase of incident energy, the adsorption rate of H atoms increases and the etching rates of C atoms and H atoms increase. H atom is more easily etched than C atom under the same energy. It is found through discussion that when the energy is greater than 1 eV during the interaction between the H atom and the hydrocarbon film, the incident H atom is firstly deposited on the surface and reacts with the surface atoms to form hydrocarbons, and then the carbon is bombarded by subsequent incident particles Hydrogen compounds desorbed on the surface, leading to the etching of C atoms, so that the C atoms were etched mainly by chemical-enhanced physical sputtering.