Non-Centrosymmetric Materials for the Generation of Atmospheric Pressure Gas Discharges

Atmospheric air plasmas are driven through large electric fields (>3 kV/mm) generated between one or more electrodes. The input voltage required to produce this electric field and to sustain a plasma in atmospheric air is often prohibitive for a number of different applications due to size, safety and cost constraints of the required power supply. To reduce the required input voltage, this works investigates inherent characteristics of certain polar non-centrosymmetric crystals to determine if they can be beneficial for discharge formation. The non-centrosymmetric arrangement of atoms within the material’s crystal structure allows for mechanical, thermal, or electrical forces to alter the crystal structure to change the magnitude of the polarization of the material. This change in polarization can lead to rapid changes in surface potential and be used to generate a discharge. Effectively, these crystals can be used to amplify applied voltages through piezoelectric, pyroelectric, and ferroelectric effects. In this work, discharges are generated in atmospheric air using non-centrosymmetric materials as natural amplifiers. By thermally-cycling a pyroelectric crystal, an atmospheric pressure gas discharge was generated through the input of heat. By applying a small electric field to a crystal, the polarization of the crystal altered, creating a sufficiently large electric field to generate a sustainable discharge. Using the electromechanical coupling of piezoelectric crystals, a small input voltage can be amplified sufficiently to generate breakdown in air. Each of these discharges are examined in depth to better understand their underlying physics. In addition, the induced ionic wind that forms from the piezoelectric-driven discharge is evaluated to determine its viability as a method to cool portable electronics devices.