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Optical and Electrical Characterization of Piezoelectric Direct Discharges Generated Using Piezoelectric Crystals

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posted on 2022-04-06, 00:00 authored by Jinyu Yang

Conventional approaches to forming a low-temperature, nonequilibrium plasma at atmospheric pressure require a high-voltage power source, which unsurprisingly constrains most of the plasma devices to laboratory settings, limiting their application as portable devices in non-laboratory, field applications. The direct piezoelectric effect of non-centrosymmetric crystals, such as lead zirconate titanate (Pb[Zr(x)Ti(1-x)]O3 (0 ≤ x ≤ 1), PZT), offers the opportunity to develop energy conversion plasma sources that remedy the reliance on a high-voltage power source by converting mechanical energy directly into plasma generation. However, limited by insufficient knowledge about mechanical-to-plasma energy conversion and its manipulation, there is, to our knowledge, no published report on using the direct piezoelectric effect to form low-temperature, nonequilibrium plasmas.

In this dissertation, PZT piezoelectric transformers (PTs) were utilized to study the fundamentals of piezoelectric-driven plasma formation and the behavior of the piezoelectric crystal when it is used to form a plasma. PTs are solid state electrical transformers that can amplify a low-voltage input to sufficiently high gains, enough to reach the breakdown threshold of air. The intrinsic electromechanical coupling and the stable performance as a plasma source make PTs a reliable model system to investigate how the piezoelectric effect can contribute to the formation of stable, low-temperature, nonequilibrium plasmas.

High-speed imaging and simultaneous current measurements are utilized to characterize the optical and electric properties of the plasma formed off the PT’s surface. Results show that this plasma shares many characteristics with conventional plasma jets but is not constrained by a guiding flow, so we refer to it as a PT free plasma jet. To better understand the chemical composition of the PT free plasma jet, spatially-resolved optical emission spectroscopy (OES) measurements were performed. Results show that the nitrogen second positive system N2 (C3Πu→B3Πg) dominates the plasma emission spectrum with intensity decreasing almost monotonically as the function of the jet length. Finally, the spatiotemporally-resolved characteristics of the electric field generated by the PT have been investigated using the electric-field induced second harmonic (E-FISH) generation technique. Results reveal the spatial distribution of the electric field around the PT’s output distal end and how it evolves in time. These studies help to develop a comprehensive understanding of PTs and piezoelectric-driven plasmas, laying the foundation for the development of a mechanical energy conversion plasma source that can be used in applications outside the laboratory.

History

Date Modified

2022-08-15

Defense Date

2022-03-29

CIP Code

  • 14.1901

Research Director(s)

David B. Go

Committee Members

Paul Rumbach William Phillip

Degree

  • Doctor of Philosophy

Degree Level

  • Doctoral Dissertation

Language

  • English

Alternate Identifier

1341049720

Library Record

6269017

OCLC Number

1341049720

Program Name

  • Aerospace and Mechanical Engineering

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