P. Hennequin | Searcharxiv

arXiv2025

Edge Radial Electric Field in Positive and Negative Triangularity Plasmas in the TCV Tokamak

We present the first edge $E_r$ measurements in negative triangularity (NT) TCV plasmas. The Doppler backscattering measurements of $v_\perp \approx E_r/B$ reveal a significant impact of triangularity on the $E_r$ well: In Ohmic, NBI, and ECRH heated discharges, the $E_r$ well and associated $E_r \times B$ shear are stronger in NT-shaped plasmas compared to their positive triangularity (PT) counterpart. This suggests a connection to the concomitant NT performance gain relative to PT L-mode.

physics.plasm-ph↗

arXiv2014

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

QuaLiKiz, a model based on a local gyrokinetic eigenvalue solver is expanded to include momentum flux modeling in addition to heat and particle fluxes. 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 ExB shear impact on the saturated potential amplitude by means of a mixing length rule. Hence, the effect of the ExB 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.

physics.plasm-ph↗