Absolute measurement of surface potential and discharge power distributions for piezoelectric transformer-based plasma reactor

A new method for absolute measurement of surface potential distributions on a Rosen-type piezoelectric transformer (PT) was investigated using a sensing electrode proposed in this study. The sensing electrode consists of a dielectric layer having striped back electrodes, arrayed in the longitudinal direction of the PT, which is basically similar to the electrode for generating a dielectric barrier discharge (DBD). An equivalent circuit was defined for each striped electrode and a constant in the circuit necessary for the estimations of the absolute surface potential distributions was determined experimentally. The absolute measurements, of the surface potential distributions of the PT were performed at (1/2)lambda mode vibration both with and without a potential divider (PD) connected to the secondary terminal. Surface potential distribution without the PD connected, i.e., the unloaded condition of the PT, is in good agreement with the theoretical curve of the surface potential distribution. Moreover, the surface potential distribution while the DBD appears and the discharge power distribution of the DBD generated by the PT was also determined at absolute values using the same electrode configurations.