Improved performance in long-pulse ELMy H-mode plasmas with internal transport barrier in JT-60U

Oyama, Naoyuki; Isayama, Akihiko; Suzuki, Takahiro; Koide, Yoshihiko; Takenaga, Hidenobu; Ide, Shunsuke; Nakano, Tomohide; Asakura, Nobuyuki; Kubo, Hirotaka; Takechi, Manabu; Sakamoto, Yoshiteru; Kamada, Yutaka; Urano, Hajime; Yoshida, Maiko; Tsuzuki, Kazuhiro*; Matsunaga, Go; Gormezano, C.*; JT-60 Team

After the installation of FSTs in JT-60U, ripple induced fast ion losses have been reduced by 1/21/3. The increase in the absorbed power at the same injection power can reduce the required number of NB units to sustain a given . The smaller recycling level and edge density, which is suitable condition to get higher edge temperature, can be kept longer. The higher edge temperature is essential in keeping the peaked pressure/temperature profile. In addition to this, smaller fast ion losses reduce the effective torque for ctr-rotation and increase in better flexibility of torque input. Then, better quality of -ITB was obtained in the plasmas with co-rotation. By making use of these advantages to sustain an ITB, the performance of long-pulse ELMy H-mode plasmas was improved in terms of sustained duration time for both high and high thermal confinement enhancement factor (). High 2.3 together with 1 was sustained for 23.1s (, where is the current diffusion time.), which also provide high . These long-pulse plasmas are possible candidates for ITER hybrid operation scenario.