Simulation of the charging process of corona electret apparatus using finite element method

In order to estimate space charging process in the corona charging apparatus which has been used to make polymer electret cells, the electrical properties of 30[/spl mu/m] thickness polypropylene films are obtained from TSC measurement after corona charging between copper knife electrode and aluminium cylinder electrode with the voltages of -8, -7, -6, and -5 [kV], respectively. The electrostatic contour and the electric field vector are calculated using finite element method with the electrical properties obtained from TSC spectra analysis. The edge effect around the edge of the knife electrode affects the electrostatic contour on the surface of the specimen and the electric field concentration inside the polymer. As a result, the uneven charging state in the electret cell due to the design error is calculated, and the optimal design of corona charging apparatus appropriate to various specimens is made practicable.<>