Study on the Effect of H on He Thermal Desorption Behavior in SIMP Steel

In order to provide a basic understanding on the effect of H on He behaviors in the structural materials for the future nuclear systems, the effect of H on He thermal desorption and retention behaviors in SIMP steels was studied using thermal desorption spectroscopy(TDS), scanning electron microscope(SEM), and transmission electron microscopy(TEM) by comparing the results of the alone irradiation of 130 keV He⁺ and the sequential irradiation of 130 keV He⁺ and 160 keV H₂⁺. The TDS results show that a major peak of He release occurred in the temperature of 1 198~1 222 K via the mechanism of bubble migration. The peak temperature of He release was lower and the release amount was larger under the sequential irradiation of He⁺ and H₂⁺ than that under the He⁺-alone irradiation. This indicates that He desorption was enhanced by the additional H irradiation. In addition, the enhancement effect of H on He thermal desorption depends on the dose of H irradiation. When the peak concentration of H increased from 5% to 50% (atom fraction), this enhancement effect was weakened. Combined with TEM and SEM results, it was found that the presence of H promoted the surface blistering during TDS heating, thus accelerating the release of He by the mechanism of bubble migration.