Temperature effects on the behavior of PET submitted to electron beam irradiation in a SEM

The electron-beam irradiation behavior of a polyethylene terephthalate (PET) has been investigated at different temperatures by the electrostatic influence method employing a scanning electron microscope (SEM). The experimental procedure is based on the measurement of displacement and leakage currents using a modified arrangement adapted to SEM able to heat the sample at controllable temperatures. The charging and flashover phenomena caused by continuous irradiation have been observed. The experimental results reveal a similar tendency for the charging process where the increase of temperature leads to an increase of the amount of accumulated charge, expect at high temperature where a different behavior is observed. For the discharging process, the increase of temperature is always followed by an increase of the released accumulated charge. The effects of the temperature on electron emission yield (EEY) where also studied. The results showed clearly a decrease in this yield with temperature for PET. The higher is the temperature and the lower is the electron emission yield.