Emission rates of CH/CD and C spectral bands for hydrocarbon-loss-events measured in JT-60U divertor plasmas

Nakano, Tomohide; Tsuzuki, Kazuhiro; Higashijima, Satoru; Kubo, Hirotaka; Asakura, Nobuyuki

Emission rates of CH and C spectral bands for CH, CD_2 loss events due to dissociation, ionization and transport were measured in JT-60U divertor plasmas. The obtained data were used for estimating the chemical sputtering yields by a spectroscopic technique. The CH loss events over one CH photon emission was about 200 at electron temperatures between 30 eV and 70 eV. These values fell within the confidential band of the CD one. The CH loss events over one CH and one C photon emission were, respectively, between 200 - 300 and between 600 - 1800, and their ratio between 3 - 6. On the assumption that only CH among hydrocarbons generated by chemical sputtering emits the C spectral bands, the intensity of the CH spectral bands originating from CH is inferred from the intensity of C spectral bands multiplied by the obtained ratio, resulting in higher than the measured CH intensity. This result indicates that dominant hydrocarbons generated by the chemical sputtering is not CH but CH.