Comparison of Saturation Rules used for Gyrokinetic Quasilinear Transport Modeling

Modeling tokamak plasmas using computer simulation can be a time-consuming and costly endeavor due to the non-linear nature of the gyrokinetic system of equations. To expedite this process, linear simulations can be employed to simplify these models. In good confinement regimes, it is reasonable to assume that the turbulent fluctuations are made up of a superposition of linear eigenmodes so that quasilinear expressions for fluxes are valid. What is more uncertain is the turbulent saturation level. Rather than choosing an ad-hoc, data-driven, or empirical saturation rule, we quickly “scan” sensitivity to the saturation rule by comparing three theory-based models capturing what is currently used in the community. The saturation rules used for this comparison are found in Bourdelle(2007), Lapillonne(2011), and Kumar(2021). In addition, we compare our three saturation rules to the widely used TGLF (Tokamak Gyro-Landau Fluid) model. The objective of this poster is to discuss and compare these saturation rules for gyrokinetic quasilinear transport modeling of linear plasma simulations conducted using GENE. Linear GENE calculations provide ion-scale eigenvalue and eigenmode information for detailed quasilinear flux estimates. A comparison of the quasilinear theory with the three saturation rules will be presented.

C. Bourdelle, X. Garbet, F. Imbeaux, A. Casati, N. Dubuit, R. Guirlet, T. Parisot 2007 Physics of Plasmas 14 112501

X Lapillonne et al 2011 Plasma Phys. Control. Fusion 53 054011

N. Kumar et al 2021 Nucl. Fusion 61 036005