Using the retarding field analyzer technique, ion energies carried by edge localized mode (ELM) filaments have been measured for the first time in the far scrape-off layer (SOL) of the ASDEX Upgrade tokamak. Energies, Ei ELM, exceeding 160 eV have been found, 5–6 cm outside the separatrix, with a decay length of about 2 cm. The measured ELM particle ion temperature in the far SOL is in the range Ti ELM ≈ 50–80 eV, in good agreement with the predictions from two simple collisionless models of ELM parallel transport. In between ELMs, Ti ≈ Te ≈ 10 eV is observed in the far SOL, consistent with relatively strong ion–electron thermal coupling in this region.
Scrape-off layer ion temperature measurements at the divertor target during type III and type I ELMs in MAST measured by RFEA