Space Charge Detection in Kapton® and PTFE Polymer Films by the Open Pulsed Electro-Acoustic Method

Abstract

Kapton® and poly(tetrafluoroethylene) (PTFE) are insulating materials that are commonly used in a space environment, notably in applications for the thermal regulation of satellites. When the satellite is in a geostationary orbit these materials are subjected to a flux of charged particles trapped in the radiation belts, and particularly to energetic electrons. They can accumulate charges due to their dielectric properties, which generate localized increases of the electric field in the material bulk that can lead to an electrostatic discharge. This phenomenon could involve serious damage to the satellite structure or performance. A behavioral study of Kapton® and PTFE materials under electronic irradiation could be helpful to understand the charge transport in the body of the material and allow a discharge control strategy to be developed. In the present study, two different measurement tools have been combined — classical surface potential measurements and Pulse Electro-Acoustic (PEA) measurements — which give information on the charge distribution in the bulk. The latter method has been further adapted for use in a vacuum during the sample irradiation and measurements under various conditions have been performed. Two measurement configurations for the irradiated sample have been studied. In the first configuration, the irradiated sample surface is grounded during the whole irradiation period. In contrast, the second configuration is one in which the irradiated sample surface is left at floating potential. Measurements made with the PEA method in both the configurations will be compared in this article, in order to determine the main physical mechanisms of charge transport occurring during the bulk sample irradiation for each irradiation configuration.