Erlangen 2026 – scientific programme
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P: Fachverband Plasmaphysik
P 7: Magnetic Confinement III
P 7.5: Talk
Tuesday, March 17, 2026, 18:05–18:30, KH 02.016
Microtearing mode turbulence and its role in high-density-gradient plasmas in Wendelstein 7-X — •Hugo Isaac Cu-Castillo1, Alejandro Bañón Navarro1, Gabriele Merlo1, Felix Reimold2, Thilo Romba2, Oliver Ford2, Sebastian Bannmann2, Markus Wappl2, Joachim Geiger2, Lila Vanó2, Alessandro Zocco2, and Frank Jenko1 for the w7-x team collaboration — 1Max-Planck-Institut für Plasmaphysik, 85748 Garching, Germany — 2Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany
Following the successful optimization of the stellarator Wendelstein 7-X (W7-X) to reduce neoclassical transport, microturbulence prevails as the primary transport mechanism limiting its plasma confinement.
Using the gyrokinetic code GENE, we demonstrate that Microtearing Modes (MTMs) dominate turbulent transport in a W7-X experimental scenario with high a/Lne, corresponding to a plasma heated purely by only Neutral Beam Injection. The appearance of MTMs is attributed to the absence of competing instabilities under these plasma conditions and the stabilizing influence of the nearly max-J configuration of W7-X. Additionally, moderate collisionality and low magnetic shear further enable the appearance of MTM. Our simulations show that, when MTM turbulence dominates, they reproduce additional experimental signatures observed in W7-X plasmas with a/Lne>1: (i) the turbulent heat flux is unaffected by the density gradient, and (ii) the electron heat channel by far exceeds the ion channel.
Keywords: Magnetic confinement; turbulent transport; gyrokinetics; Wendelstein 7-X