Study On Constant Current Corona Triode And Its Applications To Polymer Material Corona Poling

A corona is a self-sustainable discharge occurring if a sufficiently high voltage is applied to asymmetric electrodes such as a point and a plate. The advantage of the corona charging are as follows: (a) poling can be performed without deposited electrodes (b) the higher fields can be achieved than in the case of sandwich poling (c) thin films can be poled in spite of defects, because breakdowns are limited only to small sample areas.The insertion of a metallic grid, between the point and the sample to be charged allowed the control to be improved .These three-electrode systems are called triodes. Using a corona triode, one can choose the potential at which the sample is to be charged, and also achieve a uniform charge distribution at the end of the charging procedure.In this article, we describe a new version of a triode setup,allowing charging polymer foils with a constant current. With this new technique, not only charging uniformity could be substantially improved but also monitoring the sample surface potential during the charging process. To keep the charging current is constant during the charging process. We design a feedback circuit, though it control the grid voltage, so that the potential different between the grid and the sample is kept constant.The method was applied to measure the potential buildup on LDPE samples and these results are discussed. The experimental results demonstrate that the constant current triode with grid voltage control have been extensively used in the study of charge storage and charge transport of polymer.Polymers for nonlinear optics attracted interest because of the strong nonlinearity of molecular chromospheres as guests, side groups, or main-chain segments. In order to obtain second order nonlinear effects such as second harmonic generation (SHG), a non-Centro symmetric material is required. The corona triode with grid voltage control was used to pole caracole-based polymers (PVK-azoic). The setup can be provides us with a method for detecting the end of the poling process and the poling field.