Study On Photo-Stimulated Discharge And Measuring System About Polymer

The polymer is widely used in fields of electric and electronic insulation. Local electric distortion induced by space charge in polymer has a strong influence on the aging and breakdown characteristic of insulation materials. Space charge is often captured by the trap, and the trap characteristics decide charge storage and transport.Photo-stimulated discharge (PSD) and thermally stimulated current (TSC) are important tools to study structures of trap, the store and transport of charge controlled by the trap. Compared with TSC, PSD can measure more than 3eV deep charge trap in polymer. More importantly, PSD is an isothermal measurement process, which avoids the thermal erosion on trap caused by elevated temperature in TSC, so it can more accurately characterize the trap nature at a given temperature. Therefore PSD provides an effective method on measuring trap depth in the wide range of spectrum.In this dissertation, we identify the possible processes which can happen during light irradiation. Then we set up a new PSD measuring system based on tunable wavelength laser as exciting light source. The output wavelength of laser is controlled by computer. Meanwhile, the computer records the current signal measured by electrometer. We can get the spectrum about wavelength and PSD current. The trap parameters can be obtained from the spectrum. In the experiment, we firstly prove the exciting light source does not damage the structure of material by using infra-red and Raman spectroscopy, and the measuring system is very security. Then we verify the effectiveness of the system about measuring deep trap level in the polymer by PSD experiment of polyimide and polyester.