Comparison Between Dominant NBI and Dominant IC Heated ELMy H-mode Discharges in JET
The experiment described in this paper is aimed at characterizing of ELMy H-mode for plasmas with varying momentum input, rotation, power deposition profiles and ion to electron heating ratio obtained by varying the proportion between IC and NB heating. The motivation for the experiment was to verify that the basic confinement and transport properties of the baseline ITER Hmode are robust to these changes, and similar to those derived from the large database of NB heated H-modes. No significant difference in the density and temperature profiles or in the global confinement were found. Although ion temperature profiles were seen to be globally stiff, some variation of stiffness was obtained in the experiment by varying the deposition profiles, but not one that could significantly affect the profiles in terms of global confinement. This analysis shows the thermal plasma energy confinement enhancement factor to be independent of the heating mix, for the range of conditions explored. Moreover, the response of the global confinement to changes in density and power were also independent of heating mix, and were reflecting the changes in the pedestal, which is consistent with the profiles being globally stiff. Consistently, the pedestal characteristics (pressure and width) and their dependences were the same with NB or with predominant IC heating.