Divertor heat and particle control experiments on the large helical device

In the Large Helical Device (LHD), studies of divertor heat and particle control have been conducted with a helical divertor magnetic structure which exists naturally in the heliotron-type magnetic configuration to explore operation scenarios in a heliotron-type fusion reactor. Reduction of the divertor heat load has been one of the focused studies in the recent LHD experiment. Impurity seeding and modification of the edge magnetic structure with a resonant magnetic perturbation field have been investigated to enhance radiation power. To control the fueled particles and impurities, the helical diveror will be closed with a baffle structure and in-vessel cryo-sorption pump in 2012. For the examination of the baffle structure, it was partially installed in LHD in 2010. Comparison of the neutral particle pressure in the divertor with the baffle structure and with the existing open divertor shows that the baffle structure efficiently compresses fueled particles in the divertor.