Abstract:Vacuum failure of a long-lifetime Dewaris mainly due to internal outgassing. The outgassing properties of the internal material in a Dewar are tested by using a Quadrupled Mass Spectrometer (QMS). The analysis result shows that the gas consists mainly of H2O, CH4, H2 and so on.The model of outgassing properties is established according to the nonmetal outgassing theory. The result is valuable to material selection, optimization of outgassing techniques and Dewar exhausting.
