Power deposition onto plasma facing components in poloidal divertor tokamaks during type-I ELMs and disruptions

A comparative analysis of the spatial and temporal characteristics of transient energy loads (ELMs and disruptions) on plasma facing components (PFCs) in present tokamak devices and their extrapolation to next step devices is presented. Type I ELMs lead to the expulsion of energy by the plasma in helical structures with ballooning-like features and toroidal numbers in the range n = 10-15. The plasma energy is transported towards the divertor and the main chamber PFCs leading to significant transient energy loads at these two locations on small wetted area. The largest transient energy fluxes onto PFCs in tokamaks are measured during the thermal quench of disruptions. These fluxes do not exceed greatly those of large Type I ELMs, due to the much larger wetted area for energy flux during the thermal quench compared to Type I ELMs. The implications of these findings for the next step devices are discussed. (c) 2004 Elsevier B.V. All rights reserved.