Impact of negative triangularity on turbulent transport in TCV: From validated simulations to basic understanding

Negative triangularity tokamak discharges lie beyond the standard operating regimes but have been experimentally found to potentially lead to significant improvements in the plasma confinement. The physical mechanism leading to this improvement and in particular how edge triangularity, which is rapidly diminishing towards the magnetic axis, can influence the behaviour of the plasma at all radial positions still remains unclear. \\ We will discuss global gyrokinetic GENE simulations used to reproduce the transport level measured in negative triangularity L-mode TCV plasmas. Dedicated synthetic diagnostic have been successfully used to compare GENE results to experimental fluctuation measurements. Furthermore, the impact and beneficial effects of $\delta<0$ in turbulent regimes other than TEM dominated plasmas will be addressed.