At high enough electrostatic fields or after long exposure times, insulators can break down, causing large current flow through the material: this breakdown is called electrostatic discharge (ESD). ESD is a permanent, catastrophic failure of a dielectric material: what was an insulator is now essentially a conductor. Previous tests done by the USU Materials Physics Group (MPG) using our ESD custom vacuum chamber have found that, for the polymeric materials biaxially oriented polypropylene (BOPP), polyimide (PI), and low density polyethylene (LDPE), the electrostatic field strength at breakdown depends on the ramp rate of voltage applied across some materials, but possibly not others. We present more extensive ramp rate data for rates from the standard 500 V/s to two orders of magnitude slower, which are more representative of actual spacecraft charging scenarios. The voltage was incrementally increased at a constant rate across the samples until breakdown occurred. Breakdown was marked by significant current increase and continuing to rise linearly at a fixed rate set by current limiting resistors. Different ramp rate results for each polymeric material were compared to the theory applied to past experiments. Spacecraft charging is the accumulation and dissipation of charge in materials resulting from their interaction with the space environment. ESD breakdown is the main cause of failures and anomalies attributed to the spacecraft charging interactions with the space environment. Understanding these relationships between electrostatic field strength and voltage ramp rates will aid in the understanding and mitigation of ESD related anomalies and failures due to spacecraft interactions with the plasma space environment.

This work was supported by a USU Undergraduate Research and Creative Opportunities Grant and a NASA Space Technology Research Fellowship