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P: Fachverband Plasmaphysik
P 6: Magnetic Confinement II/HEPP III
P 6.1: Invited Talk
Tuesday, March 21, 2023, 11:00–11:30, CHE/0091
The physics of ELM-free regimes — •Michael Dunne1, Michael Faitsch1, Georg Harrer2, Lidija Radovanovic2, Wolfgang Suttrop1, Eleonora Viezzer3, Matthias Willensdorfer1, and Elisabeth Wolfrum1 — 1Max-Plank Institute for Plasma Physics, Bolzmannstr. 2, 85748 Garching-bei-München, Germany — 2Institute of Applied Physics, TU Wien, Fusion@ÖAW, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria — 3Dept. of Atomic, Molecular and Nuclear Physics, University of Seville, Avda. Reina Mercedes, 41012 Seville, Spain
High performance tokamak scenarios rely on an edge transport barrier (ETB) to reach the pressure and confinement time necessary for high fusion gain. The ETB is characterised by a steep pressure gradient, which provide energy for edge-localised modes (ELMs), quasi-periodic explosive instabilities, which are projected to cause significant damage to the walls of a fusion reactor. Ensuring the longevity of tokamak reactors requires, therefore, alternative operational scenarios where large ELMs are avoided. We present a general framework in which the occurrence of ELMs is understood as a combination of turbulent transport and magnetohydrodynamic (MHD) stability. Predicting and controlling ELM-free regimes is then a matter of increasing transport such that the MHD instabilities are avoided. Three ELM-free regimes are highlighted; the quasi-continuous exhaust (QCE), quiescent H-mode (QH-mode), and operation with magnetic perturbations (MPs). We present the current understanding of the physical mechanisms as well as projections to future devices.