Retention and desorption of hydrogen and helium in stainless steel wall by glow discharge

In order to evaluate the retention of hydrogen and helium and the ion impact desorption in stainless steel, the hydrogen and helium glow discharge were alternately conducted in the glow discharge apparatus with a stainless steel liner. The retained amount of hydrogen or helium in the stainless steel wall was measured based upon a residual gas analysis. The wall temperature was taken in the range from room temperature to 473 K. The retained amount of helium was observed to be large, comparable with that of hydrogen. The helium ion impact desorption for the retained hydrogen was observed to be effective, and increased with the wall temperature. The fraction of desorbed hydrogen became approximately a half of the retained amount of hydrogen. The hydrogen ion impact desorption for the retained helium, however, was observed to be negligible small. The impurity desorption owing to the hydrogen or helium glow discharge increased with the wall temperature. For reduction of the surface impurities, the hydrogen glow discharge was more effective than the helium glow discharge. The present results are useful to understand the retention and desorption of helium and hydrogen in stainless steel wall.