Göttingen 2025 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 1: Magnetic Confinment Fusion/HEPP I

P 1.4: Vortrag

Montag, 31. März 2025, 15:05–15:30, ZHG102

Gyrokinetic instabilities and turbulence in stellarators — •Linda Podavini, Per Helander, Gabriel G Plunk, and Alessandro Zocco — Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald, Germany

The stellarator Wendelstein 7-X (W7-X) is designed to achieve reduced neoclassical transport through magnetic field optimization. Its confinement properties are thus predominantly determined by turbulence, which arises from instabilities active at kinetic scales. The stability of these turbulence-driving modes depends on various plasma parameters, such as the strength of temperature and density gradients, the mirror ratio, and the rotational transform of the confining magnetic field, for instance. Adjusting these parameters offers a pathway to optimising performance in W7-X and future stellarators alike. In this contribution, we present numerical investigations of kinetic plasma turbulence in W7-X within the context of gyrokinetic theory, paying attention to possible improvements in operating scenarios and performance. The high sensitivity of these instabilities on plasma parameters underscores the need for a unified theoretical framework capable of providing rapid stability proxies. The theory of upper bounds on the growth rates of local gyrokinetic instabilities addresses this need by offering results that are independent of magnetic geometry and several plasma parameters. However, comparisons with gyrokinetic simulations highlight the crucial role of magnetic geometry in achieving quantitatively accurate results.

Keywords: Microinstabilities; Gyrokinetics; Simulations; Turbulence; Stellarators