Investigation of time-dependent polarisation charges at the interface between dielectrics

A description is given of the build up of polarisation charges at the interface of dissimilar media in a dielectric system, resulting from the sudden application of a DC electric field. The process is experimentally investigated by detecting the ponderomotive force acting on a solid dielectric located between the plates of an air-insulated parallel-plate capacitor. Measurements of such force, the variations of which take place in time scale ranging up to 105 s, are presented and discussed. Based on a simplified model of the multilayer system composed of the solid dielectric and air, analytical solutions are given for the time dependence of surface charge densities as well as of ponderomotive force. The theoretical results of the analysis are compared with the corresponding experimental data for a few solid dielectrics.