Global gyrokinetic analysis of Wendelstein 7-X discharge: unveiling the importance of trapped-electron-mode and electron-temperature-gradient turbulence

Felix Wilms; Alejandro Bañón Navarro; Thomas Windisch; Sergey Bozhenkov; Felix Warmer; Golo Fuchert; Oliver Ford; Daihong Zhang; Torsten Stange; Frank Jenko; the W7-X Team

arXiv · 2402.14403

Global gyrokinetic analysis of Wendelstein 7-X discharge: unveiling the importance of trapped-electron-mode and electron-temperature-gradient turbulence

Felix Wilms·Alejandro Bañón Navarro·Thomas Windisch·Sergey Bozhenkov·Felix Warmer·Golo Fuchert·Oliver Ford·Daihong Zhang·Torsten Stange·Frank Jenko·the W7-X Team

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Abstract

We present the first nonlinear, gyrokinetic, radially global simulation of a discharge of the Wendelstein 7-X-like stellarator (W7-X), including kinetic electrons, an equilibrium radial electric field, as well as electromagnetic and collisional effects. By comparison against flux-tube and full-flux-surface simulations, we assess the impact of the equilibrium ExB-flow and flow shear on the stabilisation of turbulence. In contrast to the existing literature, we further provide substantial evidence for the turbulent electron heat flux being driven by trapped-electron-mode (TEM) and electron-temperature-gradient (ETG) turbulence in the core of the plasma. The former manifests as a hybrid together with ion-temperature-gradient (ITG) turbulence and is primarily driven by the finite electron temperature gradient, which has largely been neglected in nonlinear stellarator simulations presented in the existing literature.

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Felix Wilms, Alejandro Bañón Navarro, Thomas Windisch, Sergey Bozhenkov, Felix Warmer, Golo Fuchert, Oliver Ford, Daihong Zhang, Torsten Stange, Frank Jenko, the W7-X Team. 2024-02-22. Global gyrokinetic analysis of Wendelstein 7-X discharge: unveiling the importance of trapped-electron-mode and electron-temperature-gradient turbulence. https://arxiv.org/abs/2402.14403

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