Photo-stimulated discharge of polyethylene charged under DC electric field or electron beam irradiation

The distribution of charge trap depth in liner low density polyethylene (LLDPE) charged either under the DC electric field of 50kV/mm or by 20 KeV electron beam irradiation was studied by photo-stimulated discharge (PSD) method. The photo-stimulated discharge spectra were recorded with the scanning wavelength from 500 nm to 200nm. The rear electrodes of the samples were either sputtered Au or the poly(ethylene-co-vinyl acetate) filled with conductive carbon black. The semitransparent Au electrode was sputtered onto the front sides. The measurement of isothermal short-circuit discharging current was also conducted immediately after the cutoff of DC voltage and the amount of the charge accumulated in the sample was compared between the specimens with different rear electrodes. It is found that there exist three to four space charge detrapping levels for different polarizing conditions. The depth and density of the traps in specimens charged by electron beam were also compared with that charged under DC electric field.