Impact of large type I ELMs on plasma radiation in JET

To prevent an unacceptable erosion of divertor targets due to ELMs in ITER, the loss in plasma stored energy should be restricted to $\Delta $W$_{ELM}$ $\sim $ 1~MJ for a single ELM. Only the JET tokamak, thanks to its size, can produce ELMs in the order of 1~MJ with energy densities comparable to those found in ITER. This contribution examines the impact of large Type~I ELMs in high current H-mode JET discharges on plasma radiation and on power load. The production of large Type~I ELMs with $\Delta $W$_{ELM}$ in the range 0.25-1.3~MJ has been demonstrated. The ELMs provoke strong radiation losses, mostly confined to the inner divertor region. Large Type~I ELMs with $\Delta $W$_{ELM~}\ge $0.72~MJ show enhanced radiation losses which are associated with the ablation of carbon layers in the inner divertor. Such large ELMs are often followed by a phase of Type~III ELMs with an increased radiation in the plasma core. In this contribution, the impact of large Type~I ELMs on plasma radiation in JET is summarized and implications of these results for ITER are discussed.