Electroluminescence measurements to detect accumulated charge at the electrode-insulator interface

Electroluminescence (EL) spectrum analysis is proposed to detect charge accumulation in insulators. The objective is to find the nature of accumulated space charges at the electrode-insulator interface by using only EL measurements recorded under a moderate ac 50 Hz field. The differences between spectra obtained with virgin samples and treated samples are analyzed. Some experience obtained with 500 /spl mu/m thick low-density polyethylene (LDPE) samples are described to illustrate the expected modification of the EL spectrum vs, interfacial space charges. Direct space charge measurements, using the laser induced pressure propagation (LIPP) method are used to verify our assumptions. Good agreement is found between EL analysis and experimental data of space charges.