Molecular dynamics simulations of amorphous hydrogenated carbon under high hydrogen fluxes
Molecular dynamics simulations of amorphous hydrogenated carbon under high hydrogen fluxes
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DOI：
10.1039/b908389h
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Goedheer, W. J.
中科院分区：
文献类型：
--
作者：
de Rooij, E. D.;von Toussaint, U.;Goedheer, W. J.
我们利用分子动力学 (MD) 研究了每 m(2) s 10(28) 离子及更高的高通量区域中碳侵蚀率和表面氢富集的通量依赖性。我们模拟了在 700 和 1000 K 的表面温度下暴露于氢能为 10 eV 的高通量氢轰击的无定形氢化碳样品。采用 Brenner-Beardmore 的反应性经验键序势作为相互作用势，并使用 Berendsen 恒温器模拟能量耗散。模拟结果表明，样品温度越高，碳侵蚀率越高，但并未表现出对氢通量的强烈依赖性。因此，模拟中观察到的上表面层的氢富集很可能不会导致实验中侵蚀量的减少。此外，对于较高的通量，侵蚀材料的组成显示 CH、C2H 和 C2H2 略有增加，而具有更多氢、C 原子和 C-2 的物质则减少。然而，侵蚀材料中的 H:C 比率没有表现出通量依赖性。
We study the flux dependence of the carbon erosion yield and the hydrogen enrichment of the surface in the high flux regime at 10(28) ions per m(2) s and higher by using molecular dynamics (MD). We simulate an amorphous hydrogenated carbon sample exposed to high flux hydrogen bombardment with a hydrogen energy of 10 eV at surface temperatures of 700 and 1000 K. As interaction potential the reactive empirical bond order potential of Brenner-Beardmore is taken and energy dissipation is simulated with the Berendsen thermostat. The simulation results show that the carbon erosion yield is higher for higher sample temperatures but does not show a strong dependence on the hydrogen flux. Hence, the hydrogen enrichment in the upper surface layer observed in the simulations most likely does not contribute to the erosion yield reduction in the experiments. Furthermore, the composition of the eroded material shows a slight increase in CH, C2H and C2H2 for higher fluxes, whereas species with more hydrogen, C atoms and C-2 are decreased. However, the H : C ratio in the eroded material shows no flux dependence.