Characterizing space vacuum contamination due to outgassing from dielectrics

The effects of temperature and surface preparation on outgassing rates for different solid dielectric materials are presented. Among the parameters which influence the electrical breakdown strength of the vacuum region are gas pressure, species, and the length of exposure of the solid dielectrics to vacuum. Breakdown measurements have indicated that the outgassed products of the different materials behave similarly at equivalent pressures. This is due to the fact that the outgassed species (primarily atmospheric gases) are similar for the different materials. However, significant differences in breakdown voltages are observed when the outgassing rate for each material is used in determining the breakdown voltage as a function of time. It was also found that increasing the temperature from room temperature to 150°C caused an order of magnitude increase in the outgassing rate. In addition, the exposure of materials to wet (humid) air was found to increase their outgassing rates by almost an order of magnitude