Stationary and transient divertor heat flux profiles and extrapolation to ITER

Experimental results on divertor heat load measurements from ASDEX Upgrade and JET are discussed. Thereby three topics are considered: (i) parameter dependence of steady state heat flux profiles, (ii) spatial distribution of the heat flux profile during type I edge localised modes (ELMs), and (iii) temporal evolution of the energy deposition during type I ELMs. No clear scaling of steady state heat flux profiles with plasma parameters is found. For different data sets a broadening of the heat flux profiles, a constant profile width, as well as a steepening with heating power is found. Extrapolation to ITER requires a review of the data. The heat flux profile is not significantly broadened during type I ELMs. Advantageous is the change of the in/out symmetry. The temporal behaviour of the energy deposition shows a strong increase of the heat flux on time scales of the ion sound speed and an exponential decay with about twice the rise time.