Abstract
The studies on the permeation of helium, neon and hydrogen through Hisilex which is a glass similar to Vycor have been made with a mass spectrometer. The obtained permeation rates of these gases through Hisilex are expressed as <5±10-7> exp (-Q/RT) which agrees well with Altemose's <4.8±10-7> exp (-Q/RT) for the rate of helium permeation through glasses. The fact that the pre-exponential factor does not depend on the kinds of gas and glass means that gases permeate with the same process through glasses. Then, if the activation energy Q is known, the permeation rates of gases through glasses are generally calculated.
It is shown that the activation energy Q depends on the van der Waals' diameter of permeat-ing atoms and molecules. From this relation, the value Q for the case of any gas through any glass can be estimated.
The permeation process is discussed and it is concluded that the steric factor is about unity and 1±10-3 for rubber and glass, respectively, and the diffusion in them is the rate determining step for the gas permeation.
