Reduced transport models for a tokamak flight simulator

In this thesis, a fast integrated transport model of the tokamak has been developed, involving all the relevant regions that participate in its evolution. The models employed are attractive for two main aspects: they are based on first principles, in order to increase their reliability, and they are analytical, requiring therefore small calculation time. Moreover, they do not rely on existing experimental data of the discharge that needs to be simulated, therefore making it a predictive tool for new discharges. Nevertheless, to build up the models, a few empirical observations are employed, more so in the outer plasma region, whereas the core region is treated fully on first-principles. The confined region is modeled in 1.5D, while the scrape-off layer (SOL) has a 0D structure. For the core region, a physics-based analytical regression based on a set of simulations with the transport model TGLF [Staebler 2005 Phys. Plasmas 12 102508] has been produced. The analytical formulae used in the fitting are based on the known relevant microinstabilities. In order to model the saturation of the pedestal pressure in the high confinement regime, an average edge-localized-modes model is applied in the pedestal region, keeping a fixed pedestal width, and a scaling on the ion power crossing the separatrix is used to determine the L-H transition. In the SOL, a two-point model for electron temperature and a 0D particle balance for the species density at the separatrix have been implemented. In the particle balance, the SOL has been virtually split in 6 neighbouring regions. In each of these regions local effects can be modeled. All the models have first been validated individually in a standalone setting. Finally, six fully integrated simulations of a low confinement scenario (#38898), and five high confinement discharges (#40446, #40009, #40254, #39977, #39967), have been performed in the Fenix flight simulator [Janky et al 2019 Fusion Eng. Des. 146 1926, Fable et al 2022 Plasma Phys. Control. Fusion 64 044002], including transients, matching the experimental trajectories. The observed differences are discussed. The comparison between simulated and measured global parameters and kinetic profiles evolution displays the quality of the produced heat transport models, which work well for all the simulated cases. Discrepancies are observed in specific conditions for the density profile, whose origins and possible solutions are discussed.