Correlation of the intensity ratio of C2/CH molecular bands with the flux ratio of C2Hy/CH4 particles

The chemical erosion of carbon materials in the edge plasma of fusion experiments is commonly quantified by the erosion yield, i.e. the ratio of chemically eroded carbon flux to the incident hydrogen flux. A common diagnostic method for the carbon particle flux is the analysis of radiation from molecular radicals: the correlation of CH radiation with methane particle fluxes. In order to take into consideration the formation of higher hydrocarbons systematic investigations in laboratory plasmas and in the plasma edge of ASDEX Upgrade are carried out. Emphasis is laid on a correlation of C2 radiation with C2Hy particle fluxes. It is suggested to use the ratio of the molecular radiation C2/CH as a monitor tool for C2Hy/CH4 particle fluxes. From divertor gas puff relative photon efficiencies are obtained. A simplified formula for the spectroscopic determination of carbon fluxes is presented which considers the formation of higher hydrocarbons.