Measurement of dust quantity and distribution collected from JT-60U

Hayashi, Takao; Asakura, Nobuyuki; Ashikawa, Naoko*; Nakano, Tomohide

A real mass densities of carbon dust collected in the baffle and divertor regions of JT-60U were investigated. On the plasma-exposed surface, large areal density of 610 mg/m is found at the upper tile of the inner divertor, which is much larger than other areas due to the soft deposition. On the other hand, as for the plasma-shadowed area, largest areal density of 5,100 mg/m was found underneath the dome structure. The total dust weights at the plasma-exposed surface and the shadowed areas were estimated to be 1.3 g and 22.2 g, respectively, assuming the toroidal symmetry. Count-based size distributions were also investigated. The average dust size of the main population is less than 20 m for both the plasma-exposed surface and the shadowed area.