A COMPARISON OF SPACE-CHARGE DISTRIBUTIONS IN ELECTRON-BEAM IRRADIATED FEP OBTAINED BY USING HEAT-WAVE AND PRESSURE-PULSE TECHNIQUES

In the present paper, heat wave (LIMM) and pressure pulse (LIPP) measu rements of the space-charge distributions in electron-beam irradiated Teflon FEP (25 mu m thick) are reported. The space-charge profiles obt ained by the two methods are compared over the whole sample thickness. From the LIMM with the back surface heat sink, the space-charge distr ibution can be found from the surface of illumination up to at least h alf of the sample thickness. For the position of the bulk space charge , the heat wave and LIPP response results agree with each other to wit hin 1 mu m. By using LIMM, an additional negative charge layer near th e surface is found if the electron-beam irradiation is carried out thr ough the metallized sample surface.