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P: Fachverband Plasmaphysik

P 16: Poster Session Plasma Physics

P 16.6: Poster

Thursday, March 19, 2026, 13:45–15:45, Redoutensaal

Gyrokinetic Turbulence in ECRH Reintroduction Scenarios in W7-X — •Emil Overduin, Josefine Henriette Elise Proll, Sebastian Bannmann, and Michael Jeffrey Gerard — Max-Planck-Institut für Plasmaphysik, Greifswald, Germany

Recently, the neoclassically optimized stellarator Wendelstein 7-X (W7-X) has seen an increase in core ion temperature above the ≈ 2 keV clamping limit in the presence of peaked density profiles. Of special interest for this work are scenarios where the strong density gradient is created by Neutral Beam Injection (NBI), which is followed by an Electron Cyclotron Resonance Heating (ECRH) reintroduction.

The ECRH reintroduction leads to an increase of the ion temperature above the clamping limit in W7-X, while at the same time the core density peaking rate is reduced (ECRH pump-out). If the ECRH power is large enough a back-transition to a higher heat transport regime is observed. The ECRH power required for a back transition to occur is strongly dependent on the magnetic configuration of W7-X. This dependence is not well understood.

Using the local gyrokinetic code GENE the microinstabilities present in the plasma at parameters relevant for the pump-out and back-transition are investigated. The aim is to contribute to understanding the effect of turbulence on the density pump-out and back-transition. To this end, the simulations are performed at different radial locations in different configurations, and use experimentally consistent equilibria, corresponding to multiple time points during the discharges.

Keywords: turbulence; gyrokinetics; core; stellarator