Effects of varying stochastic layer on edge plasma and impurity transport in 3D EMC3-EIRENE simulations of LHD

The transport properties of edge plasma and carbon impurity in the stochastic layer of the Large Helical Device (LHD) have been studied with the three-dimensional edge transport code EMC3-EIRENE. The recent development of computational meshes, which store the magnetic configurations, has been used to carry out the studies of the impact of the magnetic field structure on the edge plasma and impurity transport in the stochastic layer. The horizontal variation of the magnetic axis position (Rax) from 3.60 m to 3.90 m leads to more open flux channels connecting to the divertor and thus a stronger particle exhaust on the target, which results in a higher erosion of divertor target. Furthermore, the outboard divertor target plates suffer from the stronger erosion compared to the inboard divertor target plates for Rax = 3.90 m, which is in contrast to the case of Rax = 3.60 m. It is also found that the stronger CIV line emission is obtained at the outboard X-point region when the magnetic axis location moves outwards horizontally.