The heat flux at the edge of L-mode JET-ILW (Be wall and W divertor) pulses is studied using the gyrokinetic code Gyrokinetic Electromagnetic Numerical Experiment (GENE) in its flux-tube configuration as well as the quasi-linear turbulent transport model TGLF using the SAT2 and SAT3 saturation rules. We use reference JET-ILW plasmas with different hydrogen isotopes and isotope mixes in which a power ramp to identify the LH power threshold has been performed. The study focuses on two pulses with an effective mass of , either with pure deuterium or a 50% hydrogen–50% tritium mix. Additional power is required to trigger an H-mode in the mix (2.98 MW) compared to the pure deuterium case (1.68 MW) despite their similar effective mass. Without E × B shear, we retrieved similar flux levels between quasi-linear (TGLF) and non-linear (GENE) simulations, within the magnitude of experimental values. The inclusion of finite E × B shear levels, which are varied as input within an assumed experimentally plausible range, showed a global reduction of transport, for both energy and particles, with a stronger effect observed for the pure deuterium case than for the isotope mix case in GENE flux-tube non-linear simulations. The use of E × B shearing resulted in a 50%–80% stronger flux for the isotope mix case than for the pure deuterium case. TGLF SAT2 and SAT3 are both unable to reproduce this behaviour.
This paper investigates the impact of different hydrogen isotope mixes on edge turbulent transport in JET-ILW plasmas before the L-H transition. The study uses simulations to compare pure deuterium and a 50% hydrogen-50% tritium mix, finding that the isotope mix requires more power to trigger the H-mode transition. The inclusion of E×B shear shows a stronger flux reduction for pure deuterium than the isotope mix, suggesting the isotope mix has a more significant impact on edge turbulence.