Implantation and replacement of hydrogen isotopes in 304 stainless steel vacuum wall under RF discharge and RF-DC glow discharge

Abstract The saturation and replacement of hydrogen isotopes implanted into a 304 stainless steel vacuum wall at 300 K under RF discharge with and without DC bias potential on an RF antenna have been studied using partial pressure measurements of desorbed isotopes. The energy of ions hitting the wall was estimated to be 30–90 eV from electrostatic probe measurement for RF discharge plasmas. Nearly 90% of the desorbed gas in the isotopic exchange process was HD molecules. The amount of desorbed gas showed a tendency to saturate at a fluence of 2.3 × 10 16 cm −2 . The desorption rate can be expressed by an inverse-exponential function with time; a two-component function is normally observed. The time constant of each component is evaluated by introducing an effective trapping coefficient.