[Table of Contents]

Plasma and Fusion Research

Volume 5, S2020 (2010)

Regular Articles

Examination of Temperature Dependence of Chemical Sputtering on Graphite by Comparing the Langevin and Berendsen Thermostats
Atsushi M. ITO, Hisashi OKUMURA1), Seiki SAITO2) and Hiroaki NAKAMURA2)
National Institute for Fusion Science, Oroshi-cho 322-6, Toki 509-5292, Japan
1)
Research Center for Computational Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
2)
Department of Energy Engineering and Science, Graduate school of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-01, Japan
(Received 10 December 2009 / Accepted 22 April 2010 / Published 10 December 2010)

Abstract

Chemical sputtering on a graphite (0 0 0 1) surface due to hydrogen atom bombardment was investigated by a molecular dynamics simulation. To understand the temperature dependence of the sputtering yield of CHx and C2Hx, two thermostat methods used to control material temperature, the Langevin and Berendsen thermostats, were compared. The simulated sputtering yield of CH4 with a peak at 600 K under the Langevin thermostat agreed with experimental observations. The present simulation showed that the sputtering yield depends on the thermal relaxation time, which is the time required for the temperature to reduce and is the second key parameter for both thermostat methods. In addition, it was demonstrated that the Berendsen thermostat, which controls temperature globally, provides larger sputtering yields of CHx and C2Hy than the Langevin thermostat, which controls temperature locally.

Keywords

molecular dynamics, plasma-wall interaction, chemical sputtering, graphite, carbon

DOI: 10.1585/pfr.5.S2020

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This paper may be cited as follows:

Atsushi M. ITO, Hisashi OKUMURA, Seiki SAITO and Hiroaki NAKAMURA, Plasma Fusion Res. 5, S2020 (2010).