EMC3-EIRENE modelling of edge plasma and impurity emissions compared with the liquid lithium limiter experiment on EAST

Studies of edge plasma and impurity transport with the toroidally and poloidally localized liquid lithium limiter (LLL) on EAST have been performed by the three-dimensional (3D) edge transport code EMC3-EIRENE. The transport behavior of the Li1+ and Li2+ ions shows a non-axisymmetric distribution in the toroidal direction while an axisymmetric distribution is obtained for the Li3+ ions. The spatial structure of the charge state and excitation radiation patterns of lithium impurity can be understood by using field line tracing, which shows that the Li ions with different charge states exhibit different parallel transport behaviors. The 3D line-integrated LiII emission pattern simulated by EMC3-EIRENE shows a reasonable qualitative agreement with the experiment results measured by the CCD camera system on EAST. An unresolved issue in the LLL experiment is that the species emitting the strong visible spectrum observed around the edge plasma region cannot be distinguished by the current experimental diagnostics on EAST. The detailed numerical analysis of the carbon and deuterium emissions has been carried out to resolve this issue. The simulated deuterium emission pattern shows the same qualitative behavior as the experimental observation at the lower divertor region. The strong radiation experimentally observed at the upper divertor region is perhaps due to the mixing of the lithium and deuterium emissions.