Quasilinear Analysis in Positive and Negative Triangularity

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. Specifically, the quasilinear expression of the flux can be used in combination with a saturation rule for the toroidal mode amplitude. However, saturation rules are heuristic and difficult to rigorously derive. An investigation into three common theory-based saturation rules using a fairly accurate quasilinear expression for the fluxes computed using local linear gyrokinetic simulation will be presented and used to compare the stability of electrostatic modes in both positive and negative triangularities. We take plasma parameters from experimental H-mode profiles and magnetic equilibrium and include electrons, deuterium, and Carbon species. We find that the various saturation rules provide qualitatively similar behavior. Linear GENE calculations provide ion-scale eigenvalue and eigenmode information for detailed quasilinear flux estimates. Comparison with local nonlinear gyrokinetic simulations are discussed.