Toroidal distributions of amounts of retained gases and deposited impurities during 13th experimental campaign in the LHD

Abstract

The gas desorption behavior, and the amounts of retained gases and deposited impurities in the first wall during the 13th experimental campaign in the Large Helical Device (LHD) have been evaluated using a material probes technique. The desorption behavior of hydrogen and helium depended on the atomic composition of deposited impurities. The amount of retained hydrogen was large in the vicinity of the anodes used for the glow discharge conditioning (GDC). The amount of retained helium was small near the anodes in this campaign. The toroidal dependence on the amount of retained gas corresponded to the total time for the GDC and the gas species used for glow discharge in the final stage. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.