Retention and Desorption of Hydrogen and Helium in Inner Wall Material Used for The Large Helical Device (LHD)-Simulation experiments using a glow discharge apparatus-

In order to examine the behavior of hydrogen and helium during a glow discharge in Large Helical Device (LHD), simulation experiments using a glow discharge apparatus were conducted. The hydrogen and helium glow discharges were repeated alternately to the wall of a liner installed in the discharge apparatus, and then the retained and reduced gas amounts were measured. The amount of retained helium was approximately 1/4 of retained hydrogen. It was obvious that the retention of hydrogen or helium significantly depended on the discharge sequence. The reduction of retained helium due to hydrogen discharge was very small, whereas hydrogen retention was largely reduced by the helium discharge. The amounts of retained hydrogen and helium decreased with an increase in the liner temperature, whereas the amount of impurity desorption increased with the liner temperature.