Design and development of lower divertor for JT-60SA

Sakurai, Shinji; Higashijima, Satoru; Shibama, Yusuke; Hayashi, Takao; Ozaki, Hidetsugu; Masaki, Kei; Masuo, Hiroshige*; Shibanuma, Kiyoshi; Sakasai, Akira; JT-60SA Team

Heat removal for heat flux of 15MW/m and compatibility with remote handling maintenance are required for the lower divertor in JT-60SA. Vertical divertor targets and a private dome with V-shaped corner similar to ITER are applied to reduce heat flux by radiation enhancement. The lower divertor consists from 36 divertor cassettes with toroidal width of 10 degree for transporting through large horizontal port of vacuum vessel (VV). Each cassette is fixed on the three supports at bottom of VV. The cassette has coolant pipe connections to the coolant pipe headers in VV. The pipe connection can be cut and welded by remote handling tools. Although bolted CFC tiles on water cooled copper alloy heatsinks will be adopted for most part of divertor targets in the initial operation phase, brazed CFC monoblock targets will be applied partially. The bolted CFC targets will be replaced to CFC monoblock targets in accordance with increment of plasma heating power.