Abstract Details
Abstracts
Author: Stefan Tirkas
Requested Type: Consider for Invited
Submitted: 2024-04-05 18:26:53
Co-authors: Y. Chen, S.E. Parker
Contact Info:
University of Colorado, Boulder
390 UCB University of Colorado
Boulder, CO 80309
United States
Abstract Text:
Ion-scale gyrokinetic simulations are now able to accurately predict transport levels and power spectra; however, they can often underestimate the electron thermal transport. Recent multiscale simulations [1,2,3] have shown that including electron-scale turbulence can lead to better agreement with experimental heat flux levels and that capturing cross-scale dynamics is important. However, multiscale simulations require resolving the electron gyroradius thereby limiting simulation domain size, while accounting for global effects on the ion scale requires radial domains of hundreds of ion-gyroradii. Therefore, a subgrid model of electron-scale turbulence is of interest for modeling future burning plasma experiments using global ion-scale simulation. Here we demonstrate a subgrid ETG model that averages electron-scale turbulence from the GENE code over intermediate scales in space and time to input into global ITG GEM simulations. This approach results in ion-scale equations which include the electron heat transport from ETG turbulence and the effects of electron-scale turbulence on the ion scale. Flux-tube ETG Cyclone Base Case simulations are carried out using GENE at different radial locations and a kinetic form of the flux is added to ion-scale global GEM simulations as a source term. Analytic radial profiles of ETG heat flux are constructed and tested against flux-tube runs at multiple radial locations. Different ratios of ITG to ETG turbulent energy flux levels are considered and the results of capturing ETG heat transport in global GEM simulations are discussed. Coupling of the ETG streamer potential and intermediate-scale zonal flows found in ETG simulations to the ion-scale will be investigated [4].
[1] Maeyama S. et al 2015 Phys. Rev. Lett. 114 255002
[2] Howard N.T. et al 2016 Phys. Plasmas 23 056109
[3] Holland C. et al 2017 Nucl. Fusion 57 066043
[4] Tirkas S. et al 2023 Nucl. Fusion 63 026015 - https://doi.org/10.1088/1741-4326/acab15
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