Correlation of Type I ELM Energy Losses with Pedestal Plasma Characteristics and Global Discharge Parameters in JET ELMy H-modes

The Type I ELMy H-mode regime is the reference regime for inductive operation of ITER. A major drawback of this regime is the periodic large power loads on plasma facing components associated with Type I ELMs hat may lead to unacceptable divertor target lifetime reduction when extrapolated to next step devices. Type I ELM energy losses in JET are well correlated with the pedestal plasma parameters, but there is a considerable scatter in this dependence, indicating that other additional factors contribute in a significant way to the mechanisms determining the Type I ELM energy loss from the main plasma. In order to determine some of these additional factors, a wide range of experiments has been carried out at JET, including scans of additional heating power (6 ­18MW), deuterium fuelling rates (0 ­ 1023 s-1 ), plasma current (1.1 ­3MA), q95 (2.8 ­5.2) and plasma shaping (d = 0.20 ­ 0.43). In these experiments the ELM energy loss, pedestal parameters and gradients (only for a set of plasma configurations and plasma currents) and ELM crash characteristics (ELM energy loss,width of the ELM affected volume, duration of the ELM-crash from MHD activity, etc.) have been determined. Figure 1 shows the values of pedestal temperature and density before the Type I or III ELMs for the discharges in this study.
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