Seeding of impurities in JET H-mode discharges to mitigate the impact of ELMs

ELMy H-mode is one of the foreseen operational scenarios for ITER-FEAT. Good confinement and density is usually associated with Type I ELMs, which, however, will have a severe impact on the divertor target plates in ITER. At the JET-tokamak, impurities have been seeded into a variety of discharge configurations, by which the radiation level can be risen by a factor of 2. This delays the appearance of ELMs and reduces the power load onto the divertor target plates. In this paper, the influence of the impurities on the ELM behaviour and the plasma edge properties will be discussed. Several divertor diagnostics, such as electrical probes and infrared camera indicate a reduction of the heat power load at the inner divertor target tiles and a shrinking of the impact zone at the outer divertor.