Reduction of hydrogen and helium retention in stainless steel by argon glow discharge

Although wall conditioning using Ar glow discharges is occasionally employed to reduce helium and hydrogen retention in the inner walls of the vacuum chamber of nuclear fusion devices, the effect of an Ar glow discharge on the reduction of helium and hydrogen retention has never been systematically investigated. In the present experiment, Ar glow discharges were applied to the stainless steel walls of a glow discharge device. Residual gas analysis (RGA) clearly showed that the Ar glow discharge significantly reduced the amount of helium and hydrogen retained. It was found that the fraction of the amount of desorbed helium to the initial retained amount of helium was as high as 13% and the fraction of the amount of desorbed hydrogen to the initial amount of hydrogen was as high as 36%.