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

Abstract

Non-dimensional transport studies have been carried out for NBI heated ELMyH-mode plasmas in JT-60U. In a high-δ (triangularity) case, both theelectron thermal diffusivity, χe, and the ion thermal diffusivity,χi, show gyroBohm-like diffusion, χe/χBohm,χi/χBohm∝(ρ*)0.7-0.9, where ρ* is the normalized Larmor radius. The dependenceof the energy confinement on the normalized collision frequency, ν*,was also studied. The weak ν* dependence of the energy confinementtime, τE/τBohm∝(1/ν*)~0.3, wasalso obtained in the high-δ case. On the assumption of the sameν* dependence of τE/τBohm, theρ* dependence of χ* in the low-δ case iscompatible with the high-δ case. When the ELM activity is strong enoughto affect the global energy confinement, however, the ion energyconfinement was significantly degraded, although the electron energyconfinement still follows the gyroBohm-like diffusion.