Enhanced H-mode pedestal and energy confinement by reduction of toroidal field ripple in JT-60U

Urano, Hajime; Oyama, Naoyuki; Kamiya, Kensaku; Koide, Yoshihiko; Takenaga, Hidenobu; Takizuka, Tomonori; Yoshida, Maiko; Kamada, Yutaka; JT-60 Team

The pedestal pressure and energy confinement of H-mode plasmas were improved by the reduction of toroidal field (TF) ripple with the installation of ferritic steel tiles (FSTs) in JT-60U. The profile of toroidal rotation became less counter and the pedestal pressure is increased with FSTs particularly in case where co-NBI was used at a large volume configuration. ELM frequency was reduced and ELM energy loss was increased. For increased due to enhanced in co-direction and the reduction of TF ripple, the spatial width of H-mode pedestal became wider. The energy confinement was improved by enhancing in co-direction and by the reduction of TF ripple.