The step-electro-acoustic method for observation of the interfacial charges in insulators

The step-electro-acoustic (SEA) method for measuring the space charge distribution in insulator samples has been introduced. The principle of the SEA method, generation and detection of acoustic wave have been described. The time domain analysis of measuring system allows to obtain the relationship between the measured signal and space charge distribution in a specimen. The short circuited current in thin PVDF detector is simply related to charge profile in electret sample. The procedure of signal calibration was applied to obtain information on amount of space charge in investigated sample. The potential, electric field and space charge distributions in three-layered PTFE samples with surface charges at interfaces, which were additionally polarized with dc applied voltages, have been shown.