Multiple irradiation experiment of tungsten materials by negative hydrogen ion beam II, 1; Surface damage of multiple irradiated tungsten

Fukuda, Makoto*; Tokunaga, Kazutoshi*; Ezato, Koichiro*; Hirano, Koichiro  

Tungsten which is used as a plasma-facing material of the ITER divertor, is expected to receive various type of heat load during ITER operation. Therefore, it is necessary to understand the surface damage of tungsten under various heat load conditions. In this study, as part of the investigation of the effects of short-pulse repetitive heat loads on tungsten, the effects of multiple irradiations of the negative hydrogen ion beam (3 MeV, 5 Hz) on the surface of tungsten were investigated. As a result of the investigation, it was clarified that microcracks were formed on the surface of tungsten exposed to multiple irradiations, and that the microstructure was also changed.