スループット法による大気暴露後のガス放出速度測定とその温度依存性

Abstract

Outgassing rate measurements for each residual gas species from the ECB treated type 304L stainless steel chamber were carried out using through-put method. After one hour's air-exposure, H2O was found to be a dominant desorbed species. Other than H2O, H2, CO and CO2 were observed. Partial pressure of H2O decreased in proportion to t-1.26, which means that the activation energy of desorption of H2O is not a fixed value but has a certain distribution. The decreasing rate of H2 varied from ∝t-0.82 to ∝t-0.49, which can be explained by an assumption that the H2 outgassing is composed of the diffusive evolution of dissolved hydrogen and the associative desorption of H adatoms caused by the dissociative adsorption of H2O. The decreasing rate of CO and CO2 varied in proportion to t-0.49 and t-0.51, respectively. The total pressure was composed by the sum of the partial pressures of these four species.In accord with the variation of surrounding temperature, each partial pressure was found to fluctuate. This fluctuation is found to be useful for obtaining the physical parameters of the outgassing process.