A new technique for simultaneous measurements of space charge and TSDC in polymer films

Profiles of space charge and spectra of thermo-stimulated discharge currents (TSDC) are valuable pieces of information for the study of injection, transport and trapping of charges and polarization in insulating materials. Space charge measurements are generally realized by non destructive methods, which allow following the evolution of the density of charges but without information on their nature. On the contrary, studies of TSDC generally give information on the nature of the charges, but each run makes them disappear. Coupling the results from the two techniques is of great interest. The present work is concerned with the development of a new technique for simultaneous measurements of space charge profiles and TSDC on polymer films. A controlled thermo-electrical module is used to generate the appropriate thermal stimulations and both measurements can be made without dismantling the measuring cell. The processing of the current response to small alternative temperature variations leads to the space charge profile. The current response to a linear increase of temperature gives directly the TSDC spectrum.