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

Huber, A.; Telesca, G.; Sergienko, G.; Meigs, A. G.; Wiesen, S.; Sertoli, M.; Silburn, S.; Groth, M.; Glöggler, S.; Huber, V.; Matthews, G. F.; Linsmeier, Ch; Jachmich, S.; Wischmeier, M.; Bernert, M.; Solano, E. R.; Aleiferis, S.; Giroud, C.; Calabro, G.; Brezinsek, S.; Carvalho, P.; Mertens, Ph

doi:10.1088/1402-4896/ab5753

Journal Article

FZJ-2020-01923

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

Huber, A. (Corresponding author)FZJ* ; Wischmeier, M. ; Bernert, M. ; Wiesen, S.FZJ* ; Glöggler, S. ; Aleiferis, S. ; Brezinsek, S.FZJ* ; Calabro, G. ; Carvalho, P. ; Huber, V.FZJ* ; Sergienko, G.FZJ* ; Solano, E. R. ; Giroud, C. ; Groth, M.FZJ* ; Jachmich, S.FZJ* ; Linsmeier, C.FZJ* ; Matthews, G. F. ; Meigs, A. G. ; Mertens, P.FZJ* ; Sertoli, M. ; Silburn, S. ; Telesca, G.FZJ*

2020
The Royal Swedish Academy of Sciences Stockholm

Physica scripta T171, 014055 - (2020) [10.1088/1402-4896/ab5753]

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Please use a persistent id in citations: http://hdl.handle.net/2128/24872 doi:10.1088/1402-4896/ab5753

Abstract: 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.

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