High voltage breakdown induced by outgassing of space materials

Increasing demand for higher voltage and power levels aboard spacecrafts requires space vacuum as insulator. A concerned issue for this is whether the outgassing of dielectric materials profusely used in spacecrafts can induce breakdown, and what, if it occurs, the mechanism and characteristics are. In this paper, low pressure breakdown induced by outgassing was investigated experimentally. It’s found that vacuum breakdown is significantly facilitated by the outgassing of dielectric materials. Measurements of Paschen’s curves for typical outgassing samples show that significant decrease of breakdown voltage occurs in high vacuum region due to increase of local pressure from outgassed products. Another important mechanism that affects the breakdown voltage is the electrode surface contamination by the outgassed components. Primary models with these mechanisms taken into account are described and the model calculations agree well with the measurements. Both experimental findings and theoretical analysis indicate that outgassing of space materials is a potentially important threat to high voltage systems with vacuum as insulation.