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M. Faitsch, T. Eich, G. Harrer, E. Wolfrum, D. Brida, P. David, M. Griener, U. Stroth, . ASDEX Upgrade Team, EUROfusion MST1 Team:
"Broadening of the power fall-off length in a high density, high confinement H-mode regime in ASDEX Upgrade";
Nuclear Materials and Energy, 26 (2021), 1008901 - 1008908.

The search for scenarios in which tolerable power exhaust is combined with good confinement must involve
high separatrix densities. We present here the first infrared thermography measurements at ASDEX Upgrade
in a high density, high confinement H-mode regime in which no type-I ELMs are present. This regime was
formerly called type-II ELM or small ELM regime to distinguish it from type-I ELMs. We report on a broadening
of the power fall-off length in this regime of up to a factor of four compared to low density inter type-I ELM
conditions. This broadening is correlated to an increased filament detection rate as well as an increase in the
pressure close to the separatrix. The broadening of the fall-off length decreases the peak heat flux, while the
filaments lead to a quasi-continuous transport into the scrape-off layer and onto the divertor.

Power exhaust Scrape-off layer Infrared thermography

http://dx.doi.org/10.1016/j.nme.2020.100890

https://publik.tuwien.ac.at/files/publik_294830.pdf