Helical divertor and the local island divertor in the Large Helical Device

In the Large Helical Device (LHD), active edge plasma control using two types of divertor, helical divertor (HD) and the local island divertor (LID), is planned, respectively. The former is intrinsic in the heliotron-type magnetic configuration. In the latter case, large pumping efficiency is expected by making particle recycling localized toroidally using a divertor head and an externally produced m = 1, n = 1 island. In this paper, the divertor properties in the HD configuration are reviewed. The numerical result for design of LID is described. The results of the LID experiment performed in the Compact Helical System are also briefly reviewed.