Impurity transport modelling in the scrape off layer of the MAST tokamak using DIVIMP-OSM-EIRENE and carbon injection

Non-hydrogenic impurities play a significant role in the performance of magnetically confined fusion devices, causing increased radiation and dilution of the Deuterium-Tritium fuel isotopes. Impurities are generated at the plasma wall interfaces as well as being deliberately introduced into the plasma in order to reduce heat loads to the vessel walls. The quantity of impurities reaching the core plasma is determined by the impurity source and the nature of transport in the plasma core and scrape-off layer. Direct measurements of impurity transport have been made by injecting carbon ions into the MAST tokamak using an electrical discharge between 2 carbon electrodes. The emission of the resultant carbon plumes was measured by 2 cameras operating at 75kHz − 100kHz mounted on the MAST vessel. The resultant transport of the carbon ions parallel to the background magnetic field was then compared against simulation using the DIVIMP-OSM-EIRENE code

Influence of plasma background on 3D scrape-off layer filaments

This paper presents the effect of self-consistent plasma backgrounds including plasma-neutral interactions, on the dynamics of filament propagation. The principle focus is on the influence of the neutrals on the filament through both direct interactions and through their influence on the plasma background. Both direct and indirect interactions influence the motion of filaments. A monotonic increase of filament peak velocity with upstream electron temperature is observed, while a decrease with increasing electron density is observed. If ordered by the target temperature, the density dependence disappears and the filament velocity is only a function of the target temperature. Smaller filaments keep a density dependence, as a result of the density dependence of the plasma viscosity. The critical size δ∗, where filaments are fastest, is shifted to larger sizes for higher densities, due to the plasma viscosity. If the density dependence of the plasma viscosity is removed, δ∗ has no density dependence, but rather a temperature dependence

Impurity transport modelling in the scrape off layer of the MAST tokamak using DIVIMP-OSM-EIRENE and carbon injection

Non-hydrogenic impurities play a significant role in the performance of magnetically confined fusion devices, causing increased radiation and dilution of the Deuterium-Tritium fuel isotopes. Impurities are generated at the plasma wall interfaces as well as being deliberately introduced into the plasma in order to reduce heat loads to the vessel walls. The quantity of impurities reaching the core plasma is determined by the impurity source and the nature of transport in the plasma core and scrape-off layer. Direct measurements of impurity transport have been made by injecting carbon ions into the MAST tokamak using an electrical discharge between 2 carbon electrodes. The emission of the resultant carbon plumes was measured by 2 cameras operating at 75kHz − 100kHz mounted on the MAST vessel. The resultant transport of the carbon ions parallel to the background magnetic field was then compared against simulation using the DIVIMP-OSM-EIRENE code

Influence of plasma background including neutrals on scrape-off layer filaments using 3D simulations

This paper investigates the effect of the plasma background, including neutrals in a self-consistent way, on filaments in the scrape-off layer (SOL) of fusion devices. A strong dependency of filament motion on background density and temperature is observed. The radial filament motion shows an increase in velocity with decreasing background density and increasing background temperature. In the simulations presented here, three neutral-filament interaction models have been compared, one with a static neutral background, one with no interaction between filaments and neutrals, and one co-evolving the neutrals self consistently with the filaments. With the background conditions employed here, which do not show detachment, there are no significant effects of neutrals on filaments, as by the time the filament reaches maximum velocity, the neutral density has not changed significantly