(EX/1-3) Improved Performance in Long-pulse ELMy H-mode Plasmas with Internal Transport Barrier in JT-60U

N. Oyama1), A. Isayama1), T. Suzuki1), Y. Koide1), H. Takenaga1), S. Ide1), T. Nakano1), N. Asakura1), H. Kubo1), M. Takechi1), Y. Sakamoto1), Y. Kamada1), H. Urano1), M. Yoshida1), K. Tsuzuki1), G. Matsunaga1), C. Gormezano1), JT-60 Team
1) Japan Atomic Energy Agency, Naka, Japan

Abstract.  The performance of long-pulse ELMy H-mode plasma was improved after the installation of ferritic steel tile on JT-60U in terms of the sustained duration for both high normalized beta and high thermal confinement factor (H98). High normalized beta larger than 2.3 simultaneously with H98∼1 was sustained for 23.1 s (12 times resistive diffusion time) at q95∼3.2, which provide high normalized beta times H98 > 2.2 exceeding ITER reference scenario of 1.8. A sustainable high normalized beta times H98 for maximum duration of 28.6 s was 2.0. Improved confinement is characterized by the larger thermal components at given density maintained by smaller heating power than previous experiments. A peaked pressure profile indicating better confinement was obtained at the same shape of the heating power deposition profile in the core region (r/a < 0.6) as that in the previous experiments before the installation of ferritic steel tile.

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