Investigation of Effect of Needle Electrode Configuration on Microplasma Discharge Process in Sea Water

Gamaleev, Vladislav; Oh, Jun‐Seok; Furuta, Hiroshi; Hatta, Akimitsu

doi:10.1109/tps.2017.2669199

Cited by 12 publications

(21 citation statements)

References 29 publications

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“…More recently, Gamaleev et al highlighted the need of a more detailed study for the initial stages of the bubble formation process prior to microdischarge formation in saline solution [28].…”

Section: Introductionmentioning

confidence: 99%

Fast framing imaging and modelling of vapour formation and discharge initiation in electrolyte solutions

Asimakoulas

Graham

Krčma

et al. 2020

Plasma Sources Sci. Technol.

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The formation of vapour and initiation of electrical discharges in normal saline and other NaCl solutions has been observed and modelled. Millisecond pulses of -160 to -300 V were applied to a sharp tungsten carbide electrode immersed in the liquid. A fast framing camera was used to observe vapour layer growth around the electrode by shadowgraphy. Images were also taken without backlighting to observe emission accompanying breakdown. The conductivity of the vapour layer has been estimated by comparison of experimentally measured impedances with impedances calculated by finite element modelling of the liquid and vapour around the electrode observed by shadowgraphy. The conductivity of the vapour layer is estimated to vary between ∼ 1 and 10 −3 S/m, which are orders of magnitude higher than expected for water vapour. The reason for the high conductivity is not clear, but may be due to injection of charge carriers into the vapour by corona discharge at the sharp tip and/or the presence of cluster ions in the vapour. Alternatively, the vapour layer may be a foam mixture of high conductivity liquid and low conductivity vapour bubbles. Discharge formation does not occur primarily at the sharp tip of the electrode, but rather at the side. Finite element models of the vapour layer show that the highest electric fields are found close to the sharp tip of the electrode but that the field strength drops rapidly moving away from the tip. By contrast slightly lower, but consistently high, electric fields are often observed between the side of the electrode and the liquid vapour boundary where plasma emission is mostly observed due to the shape of the vapour liquid boundary. The electron number density in the discharge is estimated to be ∼ 10 21 m −3 . There is evidence from the shadowgraphy for different boiling mechanisms; nucleate boiling at lower voltages and film boiling at higher voltages. A rule of thumb based on a simplistic model is suggested to predict the time to discharge based on electrode area, initial current, and electrolyte temperature, density, conductivity and heat capacity.

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Section: Introductionmentioning

confidence: 99%

Fast framing imaging and modelling of vapour formation and discharge initiation in electrolyte solutions

Asimakoulas

Graham

Krčma

et al. 2020

Plasma Sources Sci. Technol.

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“…In recent study, it has been shown that OES of micro-arc discharges is advantageous for the detection of metal contaminants in seawater and could be applied to elemental composition analysis [24]. However, micro-arc discharges generated directly in liquids, especially highly-conductive liquids (such as seawater), have not been well studied and reproducible operations and reliable measurement are still a challenge [12,32,33].…”

Section: Introductionmentioning

confidence: 99%

“…The key feature of seawater is its high electrical conductivity. Due to the high conductivity, it requires a large current (typically more than 5 A) to apply the voltage required for breakdown [12,19,32,33]. The high current density passing through the liquid prior to discharge causes intense Joule heating of a small volume of liquid, resulting in the formation of microbubbles of vapor.…”

Section: Introductionmentioning

confidence: 99%

“…The high current density passing through the liquid prior to discharge causes intense Joule heating of a small volume of liquid, resulting in the formation of microbubbles of vapor. After the formation of the bubbles, micro-arc discharge is generated in a gaseous medium inside the bubble [15,19,22,32,34,35]. For the operation of plasma in such highly-conductive liquid, it is advantageous to focus the current in the small volume within the micro-sized electrode to reduce the energy required for formation of the bubbles and breakdown [12,19,32].…”

Section: Introductionmentioning

confidence: 99%

“…After the formation of the bubbles, micro-arc discharge is generated in a gaseous medium inside the bubble [15,19,22,32,34,35]. For the operation of plasma in such highly-conductive liquid, it is advantageous to focus the current in the small volume within the micro-sized electrode to reduce the energy required for formation of the bubbles and breakdown [12,19,32]. A high current density during the micro-arc discharge results in significant damage to the electrodes due to erosion [12,15,32,36].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Analysis of the Preheating Phase of Micro-Arc Discharge in Seawater, Operated Using a Needle-to-Plane Electrode with Variation in the Tip Shape

Gamaleev

Hiramatsu

Ito

et al. 2019

Plasma

Self Cite

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In this work, micro-arc discharge is investigated using a needle-to-plane electrode system placed with a micro-gap in highly conductive artificial seawater. A major problem with microarc discharge is the erosion of electrodes caused by the high current of the arc; however, it was found that erosion of the needle electrode did not have any effect on the discharge process in the case of precise control of the discharge gap. A simple mathematical model was developed for a more detailed study of the preheating phase of the discharge. The modeling showed good agreement with the experimental results and confirmed that the needle electrode could be reused to generate reproducible micro-arc discharges even after the erosion caused by the arc. Moreover, it was found that, in certain conditions, the preheating phase could be simulated using a simple inductor-capacitor-resistor (LCR) oscillator model with a resistor instead of electrodes immersed in the liquid. It was confirmed that the shape of the needle electrode’s tip did not affect the measurement of optical emission spectra in the case of precise focusing, which could be used in the development of compact analytical tools for on-site analysis of deep-sea water using atomic emission spectroscopy.

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Investigation of Micro-arc Discharge in Deep Sea Water at High Pressure

Gamaleev

Furuta

Hatta

2019

Springer Proceedings in Physics

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Investigation of Effect of Needle Electrode Configuration on Microplasma Discharge Process in Sea Water

Cited by 12 publications

References 29 publications

Fast framing imaging and modelling of vapour formation and discharge initiation in electrolyte solutions

Fast framing imaging and modelling of vapour formation and discharge initiation in electrolyte solutions

Analysis of the Preheating Phase of Micro-Arc Discharge in Seawater, Operated Using a Needle-to-Plane Electrode with Variation in the Tip Shape

Investigation of Micro-arc Discharge in Deep Sea Water at High Pressure

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