Fluid features of the stochastic layer transport in LHD

The stochastic scrape-off layer (SOL) of the helical divertor configuration in LHD exhibits a rather complex field topology where remnant magnetic islands, thin edge surfaces and stochastic field lines coexist. Using the three-dimensional edge transport code package, EMC3-EIRENE, the paper presents a numerical study of the stochastic layer transport, aimed, first of all, at clarifying to what extent the plasma as a fluid is influenced by the stochastic behaviour of the magnetic field lines. Revealed and analysed are the individual roles of different regions of the stochastic layer for plasma, impurity and neutral transport. Topics addressed and discussed are island flattening effects, flow patterns and flow damping, recycling flux suppression, rollover of divertor flux, detachment and Marfe formation and dynamics. Comparisons with experimental results are also presented.