Description
Recent validation campaigns have demonstrated that while the TGLF-SAT2 transport model accurately predicts edge temperature profiles in standard regimes, its physics fidelity remains incomplete in specific L-mode conditions \cite{angioni_confinement_2022}. In particular, modelling efforts of ASDEX Upgrade plasmas indicate towards a significant over-prediction of the ion heat flux by TGLF-SAT2 in regimes dominated by electron heating, leading to a systematic underprediction of the ion stored energy. This study utilizes the non-linear gyrokinetic code \textsc{Gene} to investigate this discrepancy and determine if high-fidelity simulations can recover the experimental transport levels. The ASDEX Upgrade discharge that is appropriate to simulate for this study is #35475 that features three distinct heating phases: an NBI-dominated phase, where reduced transport models typically perform well, a mixed-heating phase (50\% NBI - 50\% ECRH) and an ECRH dominated phase where the transport anomaly begins to manifest. Within the gyrokinetic framework this implies that the $\tau$ parameter keeps changing over the entirety of the flat-top phase of the discharge, which can significantly affect the turbulence spectrum in the plasma \cite{doerk_gyrokinetic_2016, lin_global_2007, peeters_linear_2005}. The primary objective is to verify if \textsc{Gene} predicts lower ion heat transport than TGLF-SAT2 in the electron-heated phase, thereby providing a better match to the experimental power balance while using the $\tau$ parameter as proxy to obtain a scaling for the ion and electron transport. These results aim to establish the physics basis required to improve future saturation rules and integrated modeling endeavors.