Helium Migration in Sodium Aluminosilicate Glasses

Abstract

Helium permeation, diffusion, and solubility have been measured for a number of sodium aluminosilicate glasses. The results indicate that a major change in the glass structure occurs when the alumina‐to‐soda ratio exceeds unity. It also appears that small substitutions of alumina (Al/Na<0.5) have a different effect on the glass structure than do larger (0.5<Al/Na< 1) substitutions. The mobility and solubility of helium in these glasses are influenced by the overall free volume and by the local environment of the interstices encountered by the helium atom during the diffusion process.