Non-dimensional transport study on ELMy H-mode plasmas in JT-60U

Non-dimensional transport studies have been carried out for NBI heated ELMy H-mode plasmas in JT-60U. In a high-δ (triangularity) case, both the electron thermal diffusivity, χ e , and the ion thermal diffusivity, χ i , show gyroBohm-like diffusion, χ e /χ Bohm , χ i /χ Bohm ∝(ρ*) 0.7-0.9 , where ρ* is the normalized Larmor radius. The dependence of the energy confinement on the normalized collision frequency, ν*, was also studied. The weak ν* dependence of the energy confinement time, τ E /τ Bohm ∝(1/ν*) ~0.3 , was also obtained in the high-δ case. On the assumption of the same ν* dependence of τ E /τ Bohm , the ρ* dependence of χ* in the low-δ case is compatible with the high-δ case. When the ELM activity is strong enough to affect the global energy confinement, however, the ion energy confinement was significantly degraded, although the electron energy confinement still follows the gyroBohm-like diffusion.