The Emission rates of CH, CD and C spectral bands and a re-evaluation of the chemical sputtering yield of the JT-60U carbon divertor plates

Nakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Asakura, Nobuyuki; Fukumoto, Masakatsu

We have determined the CH photon emission rate defined as the number of photons over dissociation and/or ionization event of , from the ratio of the measured emission intensity of CH spectral band to the injection rate into the divertor plasma of JT-60U. Similar photon emission rates of CD for , CH and for and have also been determined. Interestingly, during the and the injection, the spectral band intensity increases, suggesting that injected reacts with the carbon divertor plates to form heavier hydrocarbons. From the determined emission rates, previously published chemical sputtering yields, have been reevaluated. The reevaluated total chemical sputtering yield becomes lower () compared to the original () and the dependence on the incident ion flux and energy becomes weaker.