Search

Teflon Fluorinated Ethylene Propylene (FEP), used as thermal blankets on satellites, has a specific electrical behavior under space ionizing environment. Charging behaviors of this dielectric material, under electron beam irradiation, is of special interest for future spacecraft needs. Hence, ground experimental parameters have been adjusted in order to distinguish between the different physical mechanisms that steers FEP charging potential. The effect of incident electron spectrum, electric field, and dose rate has been investigated through surface potential measurements during and after the irradiation process. The experimental results especially reveal that charging potential evolution as a function of time is not strongly dependent upon the electron spectrum and the electric field but varies noticeably with dose rate. These results have been analyzed in the light of a physical model that takes into account ionization, trapping/detrapping, and recombination mechanisms for negative and positive charges. [ABSTRACT FROM PUBLISHER]

The high radiation dose received by space used polymers may greatly alter their electric properties. This effect could, for instance, reduce significantly radiation-induced conductivity (RIC) leading to high charging risks that were not predicted from pristine sample. For an optimized qualification and prediction, it is therefore highly important to characterize the charging properties of polymers and their evolution as a function of the received dose. This paper aimed at studying aging of electric properties of four different polymers (Teflon FEP, Kapton, polyepoxy DP 490 adhesive, and silicon QS1123 adhesive) at high dose level (10^5 and 10^6~Gy). We have been able to demonstrate that aging could lead to the reduction of RIC on some polymers (for polyepoxy and silicone adhesives, and FEP) or inversely to the increase of RIC on others (e.g., Kapton). Ionization effect must, however, be considered in the analysis of the results. Relaxation processes could drastically affect the charging profile and macroscopic electric properties. [ABSTRACT FROM PUBLISHER]