Comparison of theory based transport models with ASDEX Upgrade data

Heat transport in steady state ASDEX Upgrade discharges is compared with the predictions of four theory based models: the IFS/PPPL, Weiland and GLF23 models, based on ion temperature gradient (ITG) and trapped electron mode physics, and the current diffusive ballooning mode (CDBM) model. The discharges selected provide scans over heating power, density and plasma current, by varying these quantities separately. The ion temperature profiles are found to be stiff, with the same linear relation between the core and edge temperatures for all the scans considered. The ITG based models reproduce this behaviour well qualitatively and quantitatively, while the CDBM model fails to predict profile stiffness. The electron temperature, however, does change shape when the density is lowered. All models reproduce this feature qualitatively. The stored energy is well predicted by the IFS/PPPL and Weiland models. The GLF23 model is less good, showing a clear trend to underpredict the energy at higher temperatures. The predictions made with the CDBM model are rather poor.