Characteristics of Type I ELM Energy and Particle Losses in Existing Devices and their Extrapolation to ITER

Analysis of Type I ELMs from present experiments shows that ELM energy losses are correlated with the density and temperature of the pedestal plasma before the ELM crash. The Type I ELM plasma energy loss normalised to the pedestal energy is found to correlate across experiments with the collisionality of the pedestal plasma (ν*ped), decreasing with increasing ν*ped. Other parameters affect the ELM size such as the edge magnetic shear, etc., that influence the plasma volume affected by the ELMs. ELM particle losses are influenced by this ELM affected volume and are weakly dependent on other pedestal plasma parameters. In some conditions in JET and DIII-D, ELMs can be observed ("Minimum" Type I ELMs with energy losses acceptable for ITER), in which ELMs do not affect the plasma temperature. The duration of the divertor ELM power pulse is correlated with the typical ion transport time from the pedestal to the divertor target (t||Front = 2πRq95/cs,ped) and not with the duration of the ELM-associated MHD activity. Similarly, the time scale of ELM particle fluxes is also determined by t||Front. The extrapolation of present experimental results to ITER is summarised.
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