Electron heating and mode transition in dual frequency atmospheric pressure argon dielectric barrier discharge

Zhang, Z. L.; Lim, J. W. M.; Nie, Qiulin; Zhang, X. N.; Jiang, Binhao

doi:10.1063/1.5000044

Cited by 16 publications

(14 citation statements)

References 22 publications

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“…One of the crucial pieces of information in this diagnostic method is the electron energy distribution function (EEDF). The Maxwellian distribution is reasonable and acceptable in discharges at atmospheric pressure [161,162], and it was used to determine the κ ea value in the earlier works. For distributions other than Maxwellian, the κ ea value should be carefully calculated with known EEDFs.…”

Section: Practical Considerations On Diagnosticsmentioning

confidence: 99%

Electron characterization in weakly ionized collisional plasmas: from principles to techniques

Park

Choe

Moon

et al. 2018

Advances in Physics: X

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Weakly ionized plasmas at or near 1 atm pressure, or atmospheric-pressure plasmas, have received increasing attention due to their scientific significance and potential for use in a variety of applications, particularly for medicine, agriculture, and food. However, there is a large imbalance between scientific research on plasma physics and applications, which is partly due to the considerable differences in the characteristics of these plasmas compared with those of low-pressure plasmas. This discrepancy is particularly related to the difficulty in performing plasma diagnostics for highly collisional plasmas. Information on electrons (such as the electron density and temperature) is essential since electrons play a dominant role in the generation of active species related to the physical and chemical processes inside the plasma. So far, limited diagnostics have been available for electrons such as Thomson scattering and optical emission diagnostics based on equilibrium models. Here, we review the available diagnostic methods along with their merits and limitations for characterizing electrons in weakly ionized collisional plasmas. Particular attention is paid to continuum radiation-based spectroscopy, which facilitates multidimensional imaging of electron density and temperature. The future impact of these plasmas on relevant fields (i.e. laboratory and industrial plasmas and their applications) is also addressed.

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Section: Practical Considerations On Diagnosticsmentioning

confidence: 99%

Electron characterization in weakly ionized collisional plasmas: from principles to techniques

Park

Choe

Moon

et al. 2018

Advances in Physics: X

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show abstract

“…One of crucial information on this diagnostic method is the electron energy distribution function (EEDF). In this work, the Maxwellian distribution, which is reasonable and acceptable in argon glow discharges at atmospheric pressure 27 , 28 , was used to determine the κ ea value. For distributions other than Maxwellian, the κ ea value should be carefully calculated with known EEDFs.…”

Section: Methodsmentioning

confidence: 99%

Electron Information in Single- and Dual-Frequency Capacitive Discharges at Atmospheric Pressure

Park

Choe

Moon

et al. 2018

Sci Rep

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Determining the electron properties of weakly ionized gases, particularly in a high electron-neutral collisional condition, is a nontrivial task; thus, the mechanisms underlying the electron characteristics and electron heating structure in radio-frequency (rf) collisional discharges remain unclear. Here, we report the electrical characteristics and electron information in single-frequency (4.52 MHz and 13.56 MHz) and dual-frequency (a combination of 4.52 MHz and 13.56 MHz) capacitive discharges within the abnormal α-mode regime at atmospheric pressure. A continuum radiation-based electron diagnostic method is employed to estimate the electron density (ne) and temperature (Te). Our experimental observations reveal that time-averaged ne (7.7–14 × 1011 cm−3) and Te (1.75–2.5 eV) can be independently controlled in dual-frequency discharge, whereas such control is nontrivial in single-frequency discharge, which shows a linear increase in ne and little to no change in Te with increases in the rf input power. Furthermore, the two-dimensional spatiotemporal evolution of neutral bremsstrahlung and associated electron heating structures is demonstrated. These results reveal that a symmetric structure in electron heating becomes asymmetric (via a local suppression of electron temperature) as two-frequency power is simultaneously introduced.

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“…In the γ-mode, the atmospheric pressure discharge tends to localize and a DBD configuration is helpful to achieve a diffuse discharge [15], [16]. At atmospheric pressure, the transition from α-mode to γ-mode is observed in RF discharges [17]- [19] as well as in dual RF-LF discharges [20]. According to the literature, there are two distinct ways to reach the transition: either increase the electric field into the sheath by increasing the voltage amplitude [17] or increase the secondary electron emission by applying a low frequency voltage able to transport the ions to the cathode [20].…”

Section: Introductionmentioning

confidence: 99%

“…In an atmospheric pressure dual frequency (DF) plasma (14 MHz-2 MHz), increasing the voltage amplitude of the lower frequency component induces the increase of the electric field into the sheath. Ionization then takes place within the sheath and the transition from the α-mode to the γ-mode occurs [19]. The ionization mechanism shifts from wave riding to cathode secondary emission and the electron temperature increases.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric pressure dual RF–LF frequency discharge: transition from α to α – γ -mode

Magnan

Hagelaar

Chaker

et al. 2021

Plasma Sources Sci. Technol.

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This paper investigates the transition from α to α-γ-mode of a dual frequency (5 MHz/50 kHz) Dielectric Barrier Discharge (DBD) at atmospheric pressure. The study is based on both experiments and modelling of a plane/plane DBD in a Penning mixture (Ar-NH3). The discharge is in the α-RF mode with three different voltage amplitudes (250, 300 and 350 V) and biased by a low-frequency (LF) voltage with an amplitude varying from 0 to 1300 V. At a given threshold of LF voltage amplitude (of about 400 V for a 2 mm gap and 133 ppm of NH3), a transition from α to α-γ-mode occurs. It is characterized by a drastic increase of both the argon and NH emissions. Increasing the NH3 concentration leads to a decrease of the LF voltage amplitude required to reach the α-γ-mode (experiment). The transition from α to α-γ-mode is initiated when the ionization in the sheath increases and the α-γ-mode is established when this ionization becomes higher than the self-sustainment criterion (1/ γ). The transition from α to αγ-mode results in an increase of the particle densities and a stabilization of the gas voltage independently of the LF voltage amplitude. Without secondary electron emission there is no transition. In the model, increasing the secondary emission coefficient from 0.05 to 0.15 leads to a decrease of the LF voltage amplitude required to switch from α to α-γ-mode from 700 to 550 V.

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Electron heating and mode transition in dual frequency atmospheric pressure argon dielectric barrier discharge

Cited by 16 publications

References 22 publications

Electron characterization in weakly ionized collisional plasmas: from principles to techniques

Electron characterization in weakly ionized collisional plasmas: from principles to techniques

Electron Information in Single- and Dual-Frequency Capacitive Discharges at Atmospheric Pressure

Atmospheric pressure dual RF–LF frequency discharge: transition from α to α – γ -mode

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