Polarization of electron-beam irradiated LDPE films: contribution to charge generation and transport

Abstract

Electron-beam irradiation is an alternative way to generate charges in insulating materials, at controlled position and quantity, in order to monitor their behaviour in regard to transport phenomena under the space charge induced electric field or external field applied. In this study, low density polyethylene (LDPE) films were irradiated by a 80 keV electron-beam with a flux of 1 nA cm−2 during 10 min in an irradiation chamber under vacuum conditions, and were then characterized outside the chamber using three experimental methods. The electrical behaviour of the irradiated material was assessed by space charge measurements using the pulsed electro-acoustic (PEA) method under dc stress. The influence of the applied electric field polarity and amplitude has been tested in order to better understand the charge behaviour after electron-beam irradiation. Fourier transform infra-red spectroscopy (FTIR) and photoluminescence (PL) measurements were performed to evaluate the impact of the electron beam irradiation, i.e. deposited charges and energy, on the chemical structure of the irradiated samples. The present results show that the electrical behaviour in LDPE after irradiation is mostly driven by charges, i.e. by physical process functions of the electric field, and that changes in the chemical structure seems to be mild.

Modelling Charge Generation and Transport in Low Density Polyethylene Irradiated by an Electron-Beam

“…For electric fields above 40 kV/mm, this difference decreases and it seems that the shape of the characteristic for the irradiated sample draws closer to the one of the non-irradiated one. This behavior seems consistent with space charge measurements performed on post-irradiated samples, where more charges are measured compared to nonirradiated samples [2]. At higher electric fields, the charge injection becomes dominant compared to the charge generated by the electron beam, and the sample behavior comes back to a non-irradiated behavior.…”

“…Low density polyethylene (LDPE) has been used to characterize the behaviour of space charge during irradiation and post-irradiation. In the particular case of postirradiated samples where a voltage is applied, a peculiar behaviour, with strong charge build-up, has been observed [2].…”

Space Charge in Electron-Beam Irradiated Cross-Linked Polyethylene (XLPE): Charge Implantation and Release from the Bulk

“…An electron beam represents an alternative ways to build up a space charge in insulating materials, as reported using a recently built irradiation means [4,5]. The irradiation by electrons allowed to deposit charges at specific location, and to control the quantity of deposited charge with varying the beam current or the time specimen is exposed to irradiation.…”

Dynamic of Space Charge in Electron-Beam Irradiated Cross-Linked PolyEthylene

“…It seems relatively clear that dissociation of created electron-hole pairs is at the origin of the main features obtained for 100 keV electrons, besides primary electron deposition. However, the charge amount created by dissociation is not easy to anticipate [9] since most of the created pairs may recombine quickly.…”