Peculiarity of highly radiating multi-impurity seeded H-mode plasmas on JET with ITER-like wall

On JET with fully metallic first wall, highly radiative conditions with N₂, Ne and Ar as well as their mixture as radiators are approached in high density H-mode plasmas. The confinement increases from H _98(y,2) = 0.65 in unseeded pulses with γ _rad ∼ 30% to a value of H _98(y,2) = 0.75 at γ _rad ∼ 50% with N₂ injection. A degradation of the pedestal profile is compensated by steeper core n _e and T _e profiles. Further increase of γ _rad with increase of the N₂ seeding rate leads to a moderate confinement degradation which can be avoided by applying of combined impurity seeding. The enhancement of the plasma performance for the radiation fractions beyond 55% with the maximum value of H _98(y,2) = 0.78 is reached with combined N₂ + Ne and N₂ + Ar impurity injections. The observed intense, strongly localized radiation at the X-point inside the confined plasma in the scenarios with the highest radiated power fraction is interlinked to complete divertor detachment. In the JET-ILW, the X-point radiation is stable, reproducible and reversible.