ELM filament interaction with the JET main chamber

This work constitutes the first extended analysis of the spatial structure of Type-I ELM filament footprints on the JET outer limiters and upper dump plates. The data is obtained using a wide angle infrared diagnostic (with time resolution of 125 Hz) and concerns ELMs with energy in the range 0.07 ⩽ Δ W ELM / W ped ⩽ 0.32 . Type-III ELM filaments are not observed to deposit significant heat loads. The typical poloidal width of an ELM filament footprint is of order of 4–10° on the outer limiters and of order of 1–4° on the upper dump plates with weak linear dependence on the ELM size. Their quasi-toroidal mode numbers are in the range of 30–60 and 20–30, respectively.