Quartz glass diffusion and permeability

Since there are many irregular voids in the network structure of the quartz glass, the quartz glass of gas diffusion and permeation properties so many gas diffusion and permeation, is characterized by a relatively small atomic diameter gas such as helium, neon, hydrogen, etc. in the quartz glass permeation relatively large, while the atoms such as nitrogen, oxygen, relatively large and relatively small, activity of the gas, even at a temperature of 600-700^oC, penetration and diffusion in the quartz glass is lower, so the quartz glass can be used for 10^_5-10 ^{- 6}mmHg operation of vessel under negative pressure and heated, can be used in a high temperature vacuum devices.