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キーワード:
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要旨:
ELMy H-Mode experiments at JET since 2000 have focussed on the steady state and simultaneous realization of the ITER QDT=10 requirements in the normalized parameters for density, confinement and beta. Steady state phases (~ 6s or ~ 15τE) in discharges satisfying these requirements have been obtained by (i) increasing the triangularity to the ITER reference value (δ ~ 0.5) and in plasmas at low δ ~ 0.2 by seeding of Ar. Impurity seeding in high delta discharges increases the radiation level to that needed for ITER, and further increases density and confinement of unseeded reference discharges. An optimised HFS pellet injection sequence is another means to increase density and confinement. Density peaking, which would increase further ITER's performance, has been obtained with pellet injection, impurity seeding in low delta discharges and in unseeded ELMy H-Mode discharges with carefully tuned gas fuelling. Promising evidence for a reduction of the heat load caused by ELMs in high density discharges, further enhanced by impurity seeding, will be discussed. Destabilization of NTMs can limit the plasma performance and methods to avoid these will be summarized.
