Speaker
Description
Toroidal Alfvén Eigenmodes (TAEs) [1] are of significant interest in tokamak research because they can transport energetic particles and interact with turbulence. While the former poses a challenge for sustaining plasma confinement in devices like ITER and future fusion reactors [2], experimental evidence [3] suggests the latter effect could enhance plasma confinement.
We present simulations of both antenna-driven and fast ion-driven TAEs using the GYrokinetic SEmi-LAgrangian (GYSELA) code [4], a global, flux-driven, full-F, semi-Lagrangian framework designed for nonlinear gyrokinetic simulations of plasma turbulence in tokamaks. We have incorporated the mixed-variable scheme [5] to solve the Ampère equation, reducing numerical inaccuracies common in electromagnetic gyrokinetic simulations. GYSELA's capability makes it well-suited for capturing the global effects of TAEs due to their wide mode structures and large fast-ion orbits, which is necessary for future investigation of their interaction with turbulence.
In the present study, we benchmarked TAE growth rates and frequencies against ITPA reference results [6], focusing on the n=−6 TAE. A key modification to the fast ion initialization enabled the use of a canonical Maxwellian distribution, addressing limitations associated with the relaxation of pressure profiles in earlier simulations. This adjustment improved the agreement between the simulated and benchmarked TAE growth rates and frequencies with respect to fast ion temperature. We also present TAEs driven by an antenna [7], confirming their ability to generate Geodesic Acoustic Modes (GAMs) and zonal flows.
References:
[1] Cheng, C. Z., et.al. Annals of Physics 161.1 (1985): 21-47.
[2] Heidbrink, W. W. Physics of Plasmas 15.5 (2008).
[3] Mazzi, S. et al, Nature Physics 18 776 (2022).
[4] Grandgirard, Virginie, et al. Computer physics communications 207 (2016): 35-68.
[5] Mishchenko, A. et al. Physics of Plasmas 24 081206 (2017).
[6] Könies, A. et al. Nucl. Fusion 58 126027 (2018).
[7] Sadr, M. et al. Plasma Physics and Controlled Fusion 64 085010 (2022).
| Presentation type | Oral |
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