Isotope physics of DT plasmas in the core and edge of JET-ILW type-I ELMy H-modes

It is long known that the main ion mass has a strong impact on heat and particle transport in fusion plasmas. Studies of type-I ELMy H-modes performed on H, D, T and DT plasmas in the DTE2 campaign in the JET tokamak highlighted the important contribution of the pedestal stability to the overall mass dependence [1,2]. The core performance in these plasmas strongly depends on the edge values of temperature and density. T plasmas were found to outperform H and D plasmas for similar pedestal pressures at higher $\beta_{\rm N}$ which was reproduced in quasilinear simulations using TGLF-SAT2. However, open questions remained in particular regarding mixed D-T plasmas. In the DTE3 campaign a significant effort was put into extending the parameter space for D-T but also T plasmas.

The plasma edge of D-T plasmas is found closer to D conditions than those in T. We analyse these differences using a pedestal toy model which allows to model full ELM cycles using a self-consistent transport reduction due to $E\timesB$ shearing coupled with a variable stability limit. Normally, transport modelling in the edge is under determined due to the unknown particle source. However, with the ELM frequency as additional measured quantity, we reduce the possible solutions for reproducing the measured pedestal temperature and density.

In the plasma core the new data allows us to improve our predictions for the core transport. This is possible due to the density variation which for the first time is available in T as well as in D-T. With such an extended parameter space for D, DT and T at the pedestal boundary, a more precise evaluation of the validity of transport predictions with different main ion masses made with TGLF-SAT2 can be provided. Additionally, we can quantify the core contribution to the mass dependence of the global confinement.

[1] FRASSINETTI, L. et al., Nuclear Fusion 63 (2023) 112009.

[2] SCHNEIDER, P. A. et al., Nuclear Fusion 63 (2023) 112010.