Dimensional isotope scaling of heat and particle transport between JET deuterium and tritium L-mode plasmas

The dimensionally matched deuterium–tritium pulse pair under JET L-mode conditions showed 13%–16% improvement in the energy confinement time in favour of the tritium pulse. This favourable isotope scaling can be seen clearly in the effective diffusion coefficients throughout the radius. The isotope scaling originates dominantly from the electron heat transport channel and from the edge part of the plasma. The phase and amplitude profiles in response to the gas puff modulation robustly show that there is no room for a large isotope scaling in the particle transport channel in the core plasma at (Formula presented) (Formula presented). This can also be seen in the derived particle transport coefficients between the deuterium and tritium pulses. EDGE2D-EIRENE simulations found that the radial ionisation profiles are very similar between the dimensionally matched deuterium and tritium identity pulses. A similar deviation from the gyro-Bohm scaling, i.e. strong isotope scaling favouring tritium in heat transport was found with gyrokinetic simulations in the edge at (Formula presented) (Formula presented) under the JET L-mode conditions. The strong edge isotope scaling favouring tritium is consistent with the experimental observation. This edge isotope effect (Formula presented) (Formula presented) in the GENE simulations is also much larger than found in the core plasma (Formula presented) (Formula presented) when comparing similarly deuterium and tritium simulation results. Both the experimental results and the GENE simulations suggest that the isotope mass scaling is a nonlinear function of the isotope mass itself, being significantly stronger between deuterium and tritium than between hydrogen and deuterium, at least in JET L-mode conditions.