Angular momentum transport modeling: achievements of a gyrokinetic quasi-linear approach

Abstract

QuaLiKiz, a model based on a local gyrokinetic eigenvalue solver (Bourdelle et al 2002 Nucl. Fusion 42 892–902) is expanded to include momentum flux modeling in addition to heat and particle fluxes (Bourdelle et al 2007 Phys. Plasmas 14 112501, Casati et al 2009 Nucl. Fusion 49 085012). Essential for accurate momentum flux predictions, the parallel asymmetrization of the eigenfunctions is successfully recovered by an analytical fluid model. This is tested against self-consistent gyrokinetic calculations and allows for a correct prediction of the E × B shear impact on the saturated potential amplitude by means of a mixing length rule. Hence, the effect of the E × B shear is recovered on all the transport channels including the induced residual stress. Including these additions, QuaLiKiz remains ∼10 000 faster than non-linear gyrokinetic codes allowing for comparisons with experiments without resorting to high performance computing. The example is given of momentum pinch calculations in NBI modulation experiments (Tala et al 2009 Phys. Rev. Lett. 102 075001) for which the inward convection of the momentum is correctly predicted.