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G. Harrer:
"Small ELMs - A promising reactor scenario";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien; 05.11.2019.

The foreseen operational scenario for future fusion devices is the high confinement mode, which is
characterized by a strong increase in confinement due to the formation of a transport barrier at the plasma
edge. The periodic crash of this so-called pedestal is caused by large edge localized modes (type-I ELMs) which
lead to possibly intolerable heat and particle loads if not controlled. In ASDEX Upgrade, discharges with
plasma edge conditions comparable to ITER, exhibit small ELMs at good confinement, if these high density
plasmas are strongly shaped. In the experiment, type-I ELMs and small ELMs can coexist. In this contribution
a model is proposed that explains how the small ELMs modify the shape of density profile in such a way that
it is stable against large type-I ELMs. The manifestation of small ELMs at reactor-like conditions as filamentary
transport rather than large bursts offers a possible route to tolerable heat loads at high pedestal top pressure
in future devices.