Dependence of Electrostatic Field Strength on Voltage Ramp Rate for Spacecraft Materials

This paper investigated the dependence of electrostatic field strength for spacecraft materials on voltage ramp rate, by applying an increasing incremental electrostatic field until electrostatic breakdown occurred. Tests on Kapton E found that at ramp rates two or three orders of magnitude lower than the maximum recommended rate, the electrostatic breakdown field, F
_ESD
was lower by a factor of two or more. This suggests that the tabulated values of F
_ESD
, which have been used by the spacecraft charging community, could substantially overestimate F
_ESD
in common slowly evolving spacecraft situations. This paper expanded these ramp rate tests to include a wider range of ramp rates and additional materials. By contrast, Kapton TIN and biaxially oriented polypropylene (BOPP) data were found to be consistent with a single mean value F
^ESD
, rather than the proposed mean field and incremental voltage step ramp rate models.