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

Electroluminescence (EL) spectrum analysis is proposed to detect charge acc umulation in insulators. The objective is to find the nature of accumulated space charges at the electrode-insulator interface by using only EL measur ements recorded under a moderate ac 50 Hz field. The differences between sp ectra obtained with virgin samples and treated samples are analyzed. Some e xperience obtained with 500 mum thick low-density polyethylene (LDPE) sampl es 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 as sumptions. Good agreement is found between EL analysis and experimental dat a of space charges.