Analysis of the Pulsed Electro-acoustic signal treatment recorded on electron beam irradiated dielectrics
Résumé
To study the space charge distribution in the bulk of dielectric materials irradiated by an electron beam the Pulse Electro Acoustic (PEA) method has been selected. However this method offers a limited resolution and doesn’t allow the detection of injected charges when they are too close to the surface. Actually, it is difficult to separate the negative injected charges a few micrometers below the surface from positive induced surface charges. In this work, we focus our attention on the deconvolution process that is commonly used to recover the space charge distribution. The aim is to determine the more appropriate resolution factor that appears in the treatment software. A link between the resolution factor and the cutting frequency of the Gaussian filter that is introduced in the deconvolution process to get rid of the high frequency noise is established. Then, the relation between the spreading factor of the surface charge and the resolution factor introduced in the calculation is analyzed. From experimental data it is shown that the choice of the resolution factor can be of mayor importance in order to obtain an accurate space charge distribution especially at the interface.