Electrical and Optical Properties of AC Microdischarges in Porous Ceramics

Hensel, Karol; Martišovitš, V.; Machala, Zdenko; Janda, M.; Leštinský, Michal; Tardiveau, Pierre; Mizuno, Akira

doi:10.1002/ppap.200700022

Cited by 96 publications

(94 citation statements)

References 21 publications

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“…This feature was experimentally confirmed by Hensel et al [38], through measurements of the breakdown voltage in a N 2 /O 2 gas mixture. Therefore, for the same driving voltage, the discharge can more easily be created in N 2 than in O 2 , resulting in gradually slower propagation speeds of the filaments upon higher O 2 fractions in the mixture.…”

Section: Effect Of the Gas Compositionsupporting

confidence: 59%

“…This indicates that the electron attachment is not significant for a pure surface discharge. Figure 3 clearly shows that the O + 2 ions are mainly formed along the dielectric surface by the SIWs, and the maximum density is about 20 times lower than the maximum electron density for all driving voltages, because it is more difficult for the discharge to become sustained in O 2 gas [38]. This can be justified by the ionization rate shown later in Figure 5.…”

Section: Effect Of Driving Voltagesupporting

confidence: 49%

“…The effect of gas composition on the production of MDs inside porous ceramics was investigated experimentally by Hensel et al [38], using photographic visualization and optical emission spectroscopy. It was predicted that a higher O 2 content resulted in the redistribution of the MD channels inside the porousceramics [38], while the total number of MD channels was reduced, since the breakdown voltage was increased. Their results can be partially correlated to the excitation and ionization rates, which are stronger in N 2 than in O 2 , as shown in Figure 5 above.…”

Section: Effect Of the Gas Compositionmentioning

confidence: 99%

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Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

et al. 2018

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Abstract:We investigated the mode transition from volume to surface discharge in a packed bed dielectric barrier discharge reactor by a two-dimensional particle-in-cell/Monte Carlo collision method. The calculations are performed at atmospheric pressure for various driving voltages and for gas mixtures with different N 2 and O 2 compositions. Our results reveal that both a change of the driving voltage and gas mixture can induce mode transition. Upon increasing voltage, a mode transition from hybrid (volume+surface) discharge to pure surface discharge occurs, because the charged species can escape much more easily to the beads and charge the bead surface due to the strong electric field at high driving voltage. This significant surface charging will further enhance the tangential component of the electric field along the dielectric bead surface, yielding surface ionization waves (SIWs). The SIWs will give rise to a high concentration of reactive species on the surface, and thus possibly enhance the surface activity of the beads, which might be of interest for plasma catalysis. Indeed, electron impact excitation and ionization mainly take place near the bead surface. In addition, the propagation speed of SIWs becomes faster with increasing N 2 content in the gas mixture, and slower with increasing O 2 content, due to the loss of electrons by attachment to O 2 molecules. Indeed, the negative O − 2 ion density produced by electron impact attachment is much higher than the electron and positive O + 2 ion density. The different ionization rates between N 2 and O 2 gases will create different amounts of electrons and ions on the dielectric bead surface, which might also have effects in plasma catalysis.

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Section: Effect Of the Gas Compositionsupporting

confidence: 59%

Section: Effect Of Driving Voltagesupporting

confidence: 49%

Section: Effect Of the Gas Compositionmentioning

confidence: 99%

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Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

et al. 2018

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“…Then in these processes, atmospheric pressure discharges are produced in spatially confined geometries as microcavities and pores of the considered materials. However, only few studies have been performed on the physics of a discharge in contact with a porous material [Kim, 2004;Blin-Simiand et al, 2005;Guaitella et al, 2006;Sato et al, 2009;Hensel et al, 2007]. It is interesting to note that recently, Hensel [2009] showed that in microporous ceramic foams the pore size and the amplitude of the applied voltage were critical parameters for the discharge structure.…”

Section: Introductionmentioning

confidence: 99%

Simulation of the discharge propagation in a capillary tube in air at atmospheric pressure

Jánský¹,

Tholin²,

Bonaventura³

et al. 2010

J. Phys. D: Appl. Phys.

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Abstract. This paper presents simulations of an air plasma discharge at atmospheric pressure initiated by a needle anode set inside a dielectric capillary tube. We have studied the influence of the tube inner radius and its relative permittivity ε r on the discharge structure and dynamics. As a reference, we have used a relative permittivity ε r = 1 to study only the influence of the cylindrical constraint of the tube on the discharge. For a tube radius of 100 µm and ε r = 1, we have shown that the discharge fills the tube during its propagation and is rather homogeneous behind the discharge front. When the radius of the tube is in the range 300 to 600 µm, the discharge structure is tubular with peak values of electric field and electron density close to the dielectric surface. When the radius of the tube is larger than 700 µm, the tube has no influence on the discharge which propagates axially. For a tube radius of 100 µm, when ε r increases from 1 to 10, the discharge structure becomes tubular. We have noted that the velocity of propagation of the discharge in the tube increases when the front is more homogeneous and then, the discharge velocity increases with the decrease of the tube radius and ε r . Then, we have compared the relative influence of the value of tube radius and ε r on the discharge characteristics. Our simulations indicate that the geometrical constraint of the cylindrical tube has more influence than the value of ε r on the discharge structure and dynamics. Finally, we have studied the influence of photoemission processes on the discharge structure by varying the photoemission coefficient. As expected, we have shown that photoemission, as it increases the number of secondary electrons close to the dielectric surface, promotes the tubular structure of the discharge.

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“…Their gas temperature was found close to room temperature, increasing with the oxygen contents in the gas mixture. Due to the high thermal shock resistance of the ceramic foams and effective heat dissipation, the overall temporal increase of the temperature is relatively small [14,15].…”

Section: Introductionmentioning

confidence: 99%

Capillary microplasmas for ozone generation

Hensel

Machala

Tardiveau

2009

Eur. Phys. J. Appl. Phys.

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Abstract. Microplasmas inside confined cavities, pores and capillaries of dielectric materials present a great potential for various environmental applications. The paper briefly introduces the physical properties of the AC microplasmas generated by the discharges inside porous ceramics foams and focuses on their chemical effects in various mixtures of nitrogen and oxygen. Ozone formation as an example tool to evaluate the chemical potential of the microplasmas was investigated as a function of discharge power, gas mixture composition and total gas flow rate.

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Electrical and Optical Properties of AC Microdischarges in Porous Ceramics

Cited by 96 publications

References 21 publications

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

Simulation of the discharge propagation in a capillary tube in air at atmospheric pressure

Capillary microplasmas for ozone generation

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