Isotope effects in linear and saturated ohmic confinement of TCV tokamak and gyrokinetic validation

We investigated isotope effects during the tokamak à configuration variable (TCV) ohmic discharge of a diverted positive triangular shape configuration of deuterium (D) and hydrogen (H) plasmas. The transition from the linear ohmic confinement (LOC) regime to the saturated ohmic confinement (SOC) regime was clearly identified from the shot-by-shot density scan experiments. The transport characteristics were almost identical in the H and D plasmas in the LOC regime, and clear improvements were observed in the heat and particle transports in the D plasma compared with the H plasma in the SOC regime. In the SOC regime, the global energy confinement was higher in the D plasma than in the H plasma. Improvements in the SOC regime were evident in the ion channel of the heat transport and the diffusion term of the particle transport. Intrinsic toroidal rotation was found. Its profiles were identical in the H and D plasma in the LOC regime. However, the steeper gradient of toroidal rotation was found in the D plasma than in the H plasma in the SOC regime. The gyrokinetic modeling of switching ion species and keeping identical input profiles showed no difference of the heat flux in the LOC regime and a clear reduction in the D plasma heat flux in the SOC regime. Additionally, collisionality is shown to play an important role in in the heat flux reduction in D plasmas relative to H plasmas. The gyrokinetic validation of the heat transport against the experimental profiles showed a qualitative agreement regarding the heat and particle fluxes. Quantitative agreement was better for the ion heat channel than for the other transport channels.