Experimental studies on the behavior of carbon-containing molecules in the boundary plasma

Abstract

This work continues an investigation of fusion reactor materials erosion and redeposition processes, whereby the molecular collision and transport processes of carbon-containing molecules in relation to erosion and redeposition in the fusion boundary plasma were investigated. For this purpose, the graphite target was exposed to laboratory-scale hydrogen plasma, whose parameters are close to a fusion boundary plasma that generates carbon containing molecules. Optical spectroscopy was employed to identify CH, C 2 and H 2 molecules in the plasma and the spatial distribution of their relative density was measured. In addition, equations and methods are proposed to determine the excitation temperatures of carbon-containing molecules. The spatial distributions of rotational and vibrational excitation temperatures were evaluated from the obtained C 2 and CH emission spectra by fitting them with calculated spectra. We propose to test our method to monitor chemically sputtered particles near the actual Tokamak divertor.