Details of type-I ELM crashes on JET revealed using fast-sweep reflectometry

摘要

In H-mode plasmas, edge localised modes (ELMs) are responsible for large energy losses and have been observed on all major tokamaks. They have been described in machines where fast density measurements are available (ASDEX-Upgrade [1], DIII-D. [2], MAST [3], JET. [4] ...) as a fast collapse of the top of the pedestal and a rise of the scrape-off layer (SOL) density occurring in less than 200us. During the same time interval, filament structures are observed[3, 4]. The SOL density has been reported to decay in a few ms and occurs in parallel with the slower recovery of the pedestal top [4].