Turbulent transport in TCV plasmas with positive and negative triangularity

Abstract

Local gyrokinetic simulations with the GENE code are used to investigate the turbulent transport for different levels of neutral beam injection heating power in the Tokamak à Configuration Variable (TCV) for plasmas with both positive and negative edge triangularity. The sensitivity of the heat fluxes with respect to the main plasma parameters, including background gradients, impurity content, and electron temperature, is systematically studied. The experimentally measured transport levels are recovered with variations of profiles compatible with experimental error bars. When considering experimental conditions, trapped electron modes are the dominant instabilities for all heating powers and both types of shapes, whereas ion temperature gradients (ITGs) are not found. A numerical experiment, considering plasma profiles that strongly destabilize ITG modes, is thus performed. Negative triangularity is found to reduce the transport level also in this regime.