ITG heat flux reduction in JETTO-TGLF modelling of high current high performance JET pulses

A comparative transport analysis has been presented between two high current ILW JET pulses: the recent high performance pulse 92436 achieving record neutron rate and the previous record pulse 87412. JETTO-TGLF simulations predicting n_e, T_e, and T_i are able to capture the major difference in performance between the two pulses. For 92436 a very good agreement between input experimental data and predicted profiles has been achieved, while for 87412 using the same modelling assumptions the discrepancy is higher. In our attempt to find the critical parameters that separate the high and lower performance simulations, it was discovered that the predictive JETTO-TGLF simulations depend on the initial conditions. This is completely reasonable in pulses where the turbulent transport is dominated by ITG modes considering the stabilizing effect of T_i/T_e on ITG growth rates and ion heat flux. However, it implies that extrapolating simulations to different scenarios, such as those planned for the D-T campaign, may not be reliable without predicting the evolution of the plasma from the beginning of the discharge.