A ferroelectric atmospheric plasma source [abstract]
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Atmospheric plasma has applications ranging from semiconductor fabrication to surface treatment and sterilization. Typically, production of plasma requires low gas pressure and inert gasses. The ferroelectric atmospheric plasma source (FEAPS) generates plasma at atmospheric pressure and functions with a wide variety of gasses. The FEAPS offers industry and research a low cost option for plasma generation. Research on the FEAPS extends from research on a ferroelectric plasma thruster (FEPT) being developed for microspacecraft propulsion. Study of the ferroelectric plasma source was preceded by observation of high electron current densities produced under the condition of polarization switching of a ferroelectric. Polarization switching refers to applying an electric field of sufficient magnitude and direction such that the unit cell polarizations change direction. When the internal polarization vector changes direction, a substantial electric field is generated at the ceramic surface, to encourage emission of the surface charge and collection of new surface charges of the opposite sign. The non-emitting surface of the ceramic is generally covered with a solid conducting electrode, and the emitting surface is partially covered by a floating and grounded electrode. The FEAPS is a ferroelectric plasma source driven by oscillating high voltage at RF frequencies. The ferroelectric plasma source produces plasma at a surface partially covered by an electrode when the spontaneous polarization vector is reversed by application of pulsed or bipolar electric field. Ion emission is generated by the FEAPS by acceleration of the surface plasma via the ponderomotive force or an electrostatic accelerator. At the University of Missouri - Plasma Physics Engineering Technology Laboratory, undergraduate research is focusing on using the FEPT at atmospheric pressure. Goals of this research is to find optimum device parameters for plasma generation, including but not limited to gap width, applied voltage, frequency, and ferroelectric ceramic materials.