Gyrokinetic modeling of negative triangularity plasmas in ASDEX Upgrade

Negative triangularity (NT) is a promising operational regime for future reactors because it features high energy confinement without type-I ELMs. This regime has been studied at ASDEX Upgrade (AUG), which can achieve NT plasmas with average triangularity |δ_a|≈0.2 and often feature L to H-mode transitions [1]. In this work, gyrokinetic simulations are performed with the CGYRO code [2], using experimental input parameters from an NBI and ECRH heated H-mode NT plasma in AUG. Five locations across the plasma radius are modeled, and the importance of intermediate wavenumber (k_yρ_s=1.2-5.0) turbulence is investigated in the core versus edge. Gyrokinetic profile predictions are performed through the PORTALS framework [3], using optimized wavenumber ranges at each radial location. Experimental measurements of electron temperature fluctuation amplitude and frequency spectra were performed with Correlation ECE, allowing for direct comparison with simulated fluctuations.

References

[1] T. Happel et al, 2023 Nucl. Fusion 63 016002

[2] J. Candy et al, 2016 J. Comput. Physics 324 73-93

[3] P. Rodriguez-Fernandez et al, 2024 Nucl. Fusion 64 076034



Acknowledgements: Supported by the US DOE under grants DE-SC0014264, DE-SC0006419, and DE-SC0017381, and the EUROfusion Consortium (No. 101052200).