High radiation and high density experiments in JT-60U

In order to obtain improved confinement plasmas with high radiation at high density, Ar gas was injected into ELMy H mode plasmas in JT-60U. A confinement improvement of HH98(y,2) ≈ 1 was obtained with a high radiation loss power fraction (∼80%) at an electron density of ∼0.65nGW. The HH factor was about 50% higher than that in plasmas without Ar injection.