Development of internal transport barrier
scenarios at ITER-relevant high
triangularity in JET
F.G. Rimini, M. Bécoulet, E. Giovannozzi, P.J. Lomas,
O. Tudisco, B. Alper, F. Crisanti, M. de Baar, E. de La Luna,
P. de Vries, A. Ekedahl1, N. Hawkes, G. Huysmans,
X. Litaudon, V. Parail, G. Saibene, A.A. Tuccillo,
K.D. Zastrow and EFDA-JET Workprogramme Contributorsa
The development of scenarios characterized by H-mode confinement and internal transport barriers (ITBs) in high
triangularity, discharges is of particular interest for ITER advanced tokamak operation. Previous
JET experiments have shown that high triangularity favours H-modes which are ELM-free or develop type I edge
localized mode (ELM) activity, which inhibits long lasting ITBs. The recent experiments reported here concentrate
on integrated optimization of edge and core conditions. The stability of the edge pedestal was controlled using gas
injection, deuterium or light impurities, and plasma current ramps. Both methods yield more ITB-friendly edge
pedestal conditions, varying from small type I to type IIIELMsand, in extreme cases, resulting in L-mode....