Self-consistent predictive transport simulations of JET-ILW plasmas with different isotopes: a core performance sensitivity study to boundary conditions

The core transport properties of JET-ILW hybrid plasmas have been studied performing 4 channels (electron and ion heat, particle and momentum) electrostatic predictive simulations with TRANSP+TGLF(SAT1)[1]. The main aim of this work is to compare the resulting profiles when an isotope change in the main ion and NBI specie occurs, merging in a self-consistent simulation, the change in the transport properties with other collinear effects as the modification of the sources, the increase of the plasma inertia, etc. Indeed gradient driven gyrokinetic simulations of the plasma core (?=0.33) have already demonstrate that the turbulent transport is reduced for heavier isotopes [2,3], but the impact on the global profiles cannot be clearly assessed without self-consistent simulations that includes such additional effects. The followed strategy starts from predicting the core profiles (?=[0;0.8]) of a hybrid like pure Deuterium JET plasma, taken as reference case. Once obtained a proper match with the experimental profiles, a new simulation has been performed, changing the main gas isotope and the NBI gas from Deuterium (DD) to Tritium (TT). The boundary conditions for electron and ion temperature, density and rotation (respectively, Te(0.8), Ti(0.8), ne(0.8) and ?(0.8)) have not been changed, not including any pedestal isotope effect. Finally, to evaluate the impact of the pedestal isotope effect on the prediction for core TT plasma, a sensitivity scan on pedestal parameters has been performed, exploring increasing values of Ti/Te, ne and pedestal ?. The main outcome is that, despite the lower transport in TT than in DD, the ne, Ti and Te profiles are only partially affected by the isotope change because of the reduction of their core sources in TT. A momentum transport barrier (MTB) is, instead, present at ?=[0.6-0.8], where also the torque injection is larger in TT than in DD: this combination produces a faster rotating TT plasma, despite the higher mass. The sensitivity scan highlights that the MTB weakens at higher Ti/Te, but it is re-established increasing ?. The pedestal ? increase is expected according with the pedestal scaling for heavier isotopes [4].