Control of divertor heat load by Ar injection with keeping high performance in ELMy H-mode plasmas on JT-60U
S. Higashijima, N. Asakura, H. Kubo, Y. Miura, T. Nakano, S. Konoshima, K. Itami, S. Sakurai, H. Takenaga, H. Tamai and the JT-60 Team
Japan Atomic Energy Research Institute, Naka Fusion Research Establishment, Naka-machi, Naka-gun, Ibaraki-ken 311-0193, Japan
Abstract.
In JT-60U, extension of a high confinement regime toward high density and high radiation-loss-power fraction has been investigated by injecting Ar With injecting Ar and putting the outer strike point on the top of divertor dome, high confinement regime with high radiation loss power could be extended to high density region in ELMy H-mode plasmas. The confinement improvement, electron density, and radiation-loss-power fraction reached the ITER relevant regime; the thermal energy confinement time was as high as that the International Tokamak Experimental Reactor ELMy H-mode scaling IPB98(y,2), the electron density is ~80% of the Greenwald density, and the radiation-loss-power fraction is ~0.8. Moreover, the maximum divertor heat load due to ELMs has been reduced by a factor of 3 - 5 with keeping high confinement. The ELM activity can be controlled by injecting Ar and by changing the strike point position.