Bulletin of the American Physical Society
67th Annual Gaseous Electronics Conference
Volume 59, Number 16
Sunday–Friday, November 2–7, 2014; Raleigh, North Carolina
Session ET3: Dielectric Barrier Discharges and Corona |
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Chair: Anne Bourdon, Ecole Polytechnique Room: State D |
Tuesday, November 4, 2014 1:30PM - 2:00PM |
ET3.00001: Recent developments in large-scale ozone generation with dielectric barrier discharges Invited Speaker: Jose L. Lopez Large-scale ozone generation for industrial applications has been entirely based on the creation of microplasmas or microdischarges created using dielectric barrier discharge (DBD) reactors. Although versions of DBD generated ozone have been in continuous use for over a hundred years especially in water treatment, recent changes in environmental awareness and sustainability have lead to a surge of ozone generating facilities throughout the world. As a result of this enhanced global usage of this environmental cleaning application various new discoveries have emerged in the science and technology of ozone generation. This presentation will describe some of the most recent breakthrough developments in large-scale ozone generation while further addressing some of the current scientific and engineering challenges of this technology. [Preview Abstract] |
Tuesday, November 4, 2014 2:00PM - 2:15PM |
ET3.00002: Ferroelectric-driven atmospheric pressure discharges Michael Johnson, David Go Typically, dielectric barrier discharges (DBD) operate through a continuous cycle of charging and discharging a dielectric layer. Ferroelectrics are a subset of dielectrics that are inherently polarized due to their non-centrosymmetric crystal structure. The polarization of a ferroelectric has two or more stable conditions, and the polarization state can be switched by applying an electric field that exceeds the coercive field of the crystal. When the dielectric layer in a DBD is replaced with a ferroelectric, this change in polarization can lead to rapid changes in surface potential and be used to manipulate the charge on its surface. More so, these rapid changes in polarization of the crystal can cause strong electric fields at the surface that can lead to electron emission into the discharge. The coercive field of the ferroelectric allows for the occurrence of this emission to be controlled. Because of this, operating conditions of a ferroelectric barrier discharge can be altered to allow for discharges at lower AC voltages and with greater amounts of control. In this work, we investigate the potential advantages of using ferroelectrics crystals in place of dielectrics in a barrier discharge while investigating the effects of polarization and polarization shifting on the discharge. [Preview Abstract] |
Tuesday, November 4, 2014 2:15PM - 2:30PM |
ET3.00003: Self-Organization in DBDs on a Single Pulse: Periodic Structures and Diffuse Discharges Natalia Yu. Babaeva, Mark J. Kushner Self-organization in dielectric barrier discharges (DBDs) occurs in many forms, from patterns of isolated plasma filaments to more complex arrangements. This self-organization typically develops over many discharge pulses, and is often related to charging of the dielectrics. Another aspect of DBDs is the transition from filamentary to diffuse discharges. The diffuse mode can be achieved at high repetition rate over many pulses, or on a single discharge pulse using over-voltage enabled by a fast-rising applied voltage. In computational studies of DBDs using a 2-dimensional plasma hydrodynamics model, evidence has been found for self-organized-patterns (SOPs) during a single discharge pulse. The conditions are an over-voltaged DBD sustained in humid air with two dielectric layers. We first found a transition between an isolated filament and a more diffuse discharge in raising the applied electric field to approximately 100 kV/cm. The diffuse discharge is sensitive to the surface-ionization-waves (SIWs) that propagate along both dielectrics, and the relative permittivity of those dielectrics. Upon increasing voltage further, SOPs are formed by periodic ionization waves launched into the gap from the edges of the SIWs. The gap-crossing ionization waves may be either positive or negative depending on the relative capacitance of the top and bottom dielectrics. [Preview Abstract] |
Tuesday, November 4, 2014 2:30PM - 2:45PM |
ET3.00004: Charge transfer in surface barrier discharge on $\mu$ sec to msec time scales Sergey Leonov, Igor Adamovich, Vitaly Petrishchev The paper presents experimental results characterizing dynamics of development and kinetics of energy coupling in surface dielectric barrier discharge (SDBD), sustained over dielectric and weakly conducting liquid surfaces, over a wide range of time scales and electrical conductivities. Time-resolved discharge development and mechanisms of coupling with quiescent air are analyzed using nanosecond gate camera imaging, high-sensitivity time-resolved schlieren imaging, surface charge sensor, and Laser Differential Interferometry. It is shown that NS SDBD plasmas generate high-amplitude, broadband, stochastic, point-wise, near-surface perturbations on a long time scale (\textgreater 100 $\mu$s) after the discharge pulse. These perturbations are caused by discharge contraction and originate from the ends of individual streamers where they attach to the surface. It is also demonstrated a significant increase of energy (surface charge) stored on the dielectric surface during the NS discharge pulse, which in this case greatly exceeds energy dissipated as Joule heat (up to a few hundred percent). The present results strongly suggest that surface charge accumulation, along with use of alternating polarity pulse waveform, may significantly improve performance of surface discharge plasma actuators. [Preview Abstract] |
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