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Simulations of plasma turbulence in a lower single-null magnetic configurations are presented. The plasma dynamics is modelled by the drift-reduced two-fluid Braginskii equations that are coupled with a kinetic model for a single neutral species that considers ionization, charge–exchange, recombination and elastic collisions. The effect of increased core fuelling on the plasma scrape-off layer (SOL) density and temperature profile is investigated. The increase in core fuelling leads to an increase of the e-folding length in the near SOL and, in the far SOL, to an increase of the plasma density. These results are in agreement with experimental measurements, and in particular with the observations of the formation of a density shoulder in high-fuelling scenarios. The physical mechanisms underlying the increase of the far SOL density are analysed comparing parallel and perpendicular fluxes in the SOL and considering also simulations with similar parameters but without neutrals. Despite the increase of the blob size, the increase of the far SOL density observed at high-fuelling rates is found to be mainly caused by the strong decrease of parallel transport, due to the cooling of electrons resulting from ionization events.

A self-consistent model is presented for the simulation of a multi-component plasma in the tokamak boundary. A deuterium plasma is considered, with the plasma species that include electrons, deuterium atomic ions and deuterium molecular ions, while the deuterium atoms and molecules constitute the neutral species. The plasma and neutral models are coupled via a number of collisional interactions, which include dissociation, ionization, charge-exchange and recombination processes. The derivation of the three-fluid drift-reduced Braginskii equations used to describe the turbulent plasma dynamics is presented, including its boundary conditions. The kinetic advection equations for the neutral species are also derived, and their numerical implementation discussed. The first results of multi-component plasma simulations carried out by using the GBS code are then presented and analyzed, being compared with results obtained with the single-component plasma model.

A local magnetic equilibrium model is presented, with finite inverse aspect ratio and up-down asymmetrically shaped cross section, that depends on eight free parameters. In contrast with other local equilibria, which provide simple magnetic-surface parametrisations at the cost of complex poloidal-field flux descriptions, the proposed model is intentionally built to afford analytically tractable magnetic-field components. Therefore, it is particularly suitable for analytical assessments of equilibrium-shaping effects on a variety of tokamak-plasma phenomena.