The filamentary structure of ELMs in the scrape-off layer in ASDEX Upgrade

The filamentary structure in the SOL of ASDEX Upgrade during type-I ELMs was investigated by combined measurements of reciprocating Mach probe, filament probe – a combination of Langmuir probes and magnetic sensor for the radial component of the magnetic field, and IR-thermography of the reciprocating probe head. A correlation along field lines between the Langmuir probes was found, confirming the field aligned structure of the observed filaments. The ELM radial e-folding lengths of particle and heat flux are comparable (about 2 cm). This may be explained by an approximately constant ion temperature well above the electron temperature in the far SOL. The ion temperature estimated from the comparison of heat and particle flux is about 30–60 eV.