国際発表 | 8th H-mode Workshop

Energy Confinement Scaling for Reversed-shear Plasmas with Internal Transport Barrier in JT-60U

Tomonori Takizuka, Yoshiteru Sakamoto, Takeshi Fukuda, Takaaki Fujita, Yutaka Kamada, Takahiro Suzuki, Syunsuke Ide and Hiroshi Shirai
Japan Atomic Energy Research Institute, Ibaraki 311-0193, Japan

Abstract.
An energy confinement scaling for reversed-shear plasmas with box-type internal transport barrier (ITB) and L-mode edge is developed based on the JT-60U data. The stored energy is divided into two parts, L-mode base part and core part surrounded by the ITB. The core stored energy Wcore does not simply increase with the net heating power P_net. A scaling of core stored energy is given as W_scale = C ε_f^-1 B_p,f² V_core, where ε_f is the inverse aspect ratio at ITB foot, B_p,f is the poloidal magnetic field at outer midplane ITB foot, and V_core is the core volume inside ITB foot. This scaling is equivalent to the condition for the core poloidal beta ε_f β_p,core = C₁ with C₁ ≈ 1/4. Though W_core is little dependent on P_net, the estimated heat diffusivity in the ITB region moderately correlates with a neo-classical diffusivity, and the neo-classical transport is not inconsistent with the data. Physics background of the present scaling is discussed.