Effect of gamma-ray irradiation on surface charge decay through bulk of epoxy resin

This paper presents study aimed at understanding the effect of gamma-ray irradiation on surface charge decay through bulk of epoxy resin. Laminated epoxy resin was employed as test sample which was irradiated in air up to 100 kGy and then up to 1000 kGy with dosage rate of 10 kGy / h by using a ⁶⁰Co gamma-source before the test. Surface charge was introduced by corona charging method and surface potential decay dynamics was monitored with an electrostatic voltmeter. Trap distribution as well as effective charge mobility was estimated from the potential decay measurements. Obtained results show that surface potential decays bi-exponentially regardless of the polarity. Two-trap-center characteristics appear for both electron and hole in epoxy resin, the density as well as the depth in the trap center varies with the total dose. Effective charge mobility decreases initially then tends to increase with the total dose grows from 0 kGy to 1000 kGy. The change in the decay behavior of surface charge is attributed to the variation of chemical and physical structures of epoxy resin caused by the irradiation.