Flashover Prevention of High Voltage Piezoelectric Transformers by Thin Film Encapsulation

Piezoelectric transformers (PTs) are used as step-up voltage elements in many devices. The University of Missouri is developing a PT as an accelerator for an ion beam. In cases where high-voltage pulses are desired, discharges can result from a large electric field near triple point junctions. Due to the small scale of the device, conductive triple point shields are difficult to employ to prevent flashover. This paper presents an investigation of piezoelectric flashover prevention by thin film encapsulation. Dielectric material was deposited on the PT both over the entire device and at specific regions of interest. The dielectric was deposited by evaporation to eliminate gaps at the triple point. The flashover strength is evaluated depending on the dielectric type, thickness, and length. The mechanical loss incurred by the deposition is evaluated to determine if it hinders the motion of the transformer.