Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 12: Poster II

P 12.23: Poster

Tuesday, February 27, 2024, 16:30–18:30, ELP 6: Foyer

Validation of theoretical upper bounds on local gyrokinetic instabilities — •Linda Podavini, Per Helander, Gabriel Plunk, and Alessandro Zocco — Max-Planck-Institut für Plasmaphysik, Wendelsteinstraße 1, 17491 Greifswald, Germany

Turbulence in magnetic confinement fusion devices is driven by the presence of microinstabilities. In the last decades these instabilities have been studied considering various assumptions about plasma parameters and magnetic geometry, thus hampering a desirable unified theory.

The theory of upper bounds on the growth rates of local gyrokinetic instabilities [1,2,3] aims at filling this gap by introducing results which are valid for all microinstabilities. Moreover, they are independent of magnetic geometry and many plasma parameters, such as the number of particle species, beta and collisions.

We compare the upper bounds to solutions of the linear gyrokinetic equation. The latter are obtained through flux-tube simulations performed with the gyrokinetic code stella. The validation focuses on fusion-relevant instabilities and it is carried out for different magnetic field geometries and plasma parameters, to highlight the universality of the theory. The validation also includes a comparison with analytical results obtained in simple magnetic field geometries.

[1] P. Helander, and G. G. Plunk, PRL (2021)

[2] P. Helander, and G. G. Plunk, JPP (2022)

[3] G. G. Plunk and P. Helander, JPP (2022)

Keywords: microinstabilities; gyrokinetics; simulations