HEAT DEPOSITION ON THE FIRST WALL DUE TO ICRF-INDUCED LOSS OF FAST IONS IN JT-60U

In JT-60U, the heat deposition on the first wall due to the ICRF-induc ed loss of fast ions was investigated by changing the position of the resonance layer in the ripple-trapping region. A heat spot appears on the first wall of the same major radius as the resonance layer of the ICRF waves. The broadening of the heat spot in the major radius direct ion is consistent with that of the resonance layer due to the Doppler broadening. The heat spot is considered to be formed by the ICRF-induc ed ripple-trapped loss of fast ions. Although the total ICRF-induced l oss power to the heat spot is as low as 2% of the total ICRF power, th e additional heat flux will become a new issue because of the localize d heat deposition on the first wall.