The variation of confinement with elongation and triangularity in ELMy H-modes on JET

This paper describes a series of experiments undertaken in 1999 that were specifically designed to elucidate the roles of elongation and triangularity on the confinement in the steady-state ELMy H-mode regime. The new results are discussed in the context of results from earlier experiments on JET and other diverted tokamaks where the role of triangularity has been investigated. The behaviour of the H-mode transport barrier (the pedestal) and the confinement are presented in some detail for the new experiments. The picture which emerges from the data is complex and not described entirely satisfactorily by current global scaling models. The implications for ITER-FEAT are explored and found to be favourable and some possible avenues for future experiments on JET are described.