The diffusion of He through the walls of high-purity fused quartz hollow cylinders was studied using a mass spectrometer. By surrounding the outside of the hollow cylinder with He and letting it diffuse through into the mass spectrometer, permeation rates and diffusion coefficients were measured at 24 to 1034C. The activation energy was found to be different at 24 to 300C, as compared with 300 to 1034C. In the low-temperature range, the diffusion was described by:

D(cm2/s) = 3.04 x 10-4 exp[5.58(kcal/g-atom)/RT]

and in the high-temperature range by:

D(cm2/s) = 7.40 x 10-4 exp[-6.613(kcal/g-atom)/RT]

D.E.Swets, R.W.Lee, R.C.Frank: The Journal of Chemical Physics, 1961, 34[1], 17-22