Radiation loads onto plasma-facing components of JET during transient events – Experimental results and implications for ITER☆

Abstract This contribution examines the impact on plasma radiation and on power load to the divertor (i) of large type I ELMs with energies 0.25–1.3 MJ in high current H-mode JET discharges and (ii) of disruptions. (i) The ELMs provoke strong radiation losses, mostly confined to the inner divertor region. Large type I ELMs with Δ W ELM  ⩾ 0.72 MJ show enhanced radiation losses which are associated with the ablation of carbon layers in the inner divertor. Such large ELMs are usually followed by a phase of type III ELMs with an increased radiation in the plasma core. (ii) The unmitigated disruptions exhibit small radiation fractions with strong poloidal radiation asymmetry during the thermal quench, which could cause Be melting by radiation in ITER. In dedicated experiments on massive gas injection, about 60% of the thermal energy and a significant part of the magnetic energy was converted in radiation and spread uniformly over the first walls.