Anisotropic Graphite Erosion in Low-Temperature and High-Density Deuterium Plasma

概要

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The interaction between a hydrogen plasma and carbon materials is one of the important issues in low-temperature plasmas for both nuclear fusion science and plasma processing. To investigate the anisotropic characteristics of graphite erosion by deuterium bombardment, highly oriented pyrolytic graphite (HOPG) was exposed to deuterium plasmas in a newly developed toroidal plasma device. Two different plasmas with electron temperatures were used for irradiation: an ionizing plasma with an electron temperature of {\sim}3 eV and a recombining plasma with an extremely low electron temperature of {\sim}0.1 eV. Irradiations reveal clear differences between the ionizing and recombining plasmas. By surface analysis using scanning electron microscopy and Raman spectroscopy, it was found that the HOPG irradiated with the ionizing plasma has more severe damage than that irradiated with the recombining plasma. The anisotropic characteristics of graphite erosion are discussed on the basis of the results of the comparison with molecular dynamics simulation.
2012-01-25