Observation of the development of pulsed discharge inside a bubble under water using ICCD cameras

Takahashi, Katsuyuki; Takayama, Hirotoshi; Kobayashi, Shota; Takeda, Masahiro; Nagata, Yusei; Karashima, Kazuki; Takaki, Koichi; Namihira, T.

doi:10.1016/j.vacuum.2020.109690

Cited by 6 publications

(6 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results obtained by numerical simulation also show that a large part of the discharge inside the bubble propagates along with the bubble with similar size of bubbles [33,34]. The propagation velocity of the discharge is 2.7-3.6 Â 10 5 m/s in the Ar gas bubble [32] and 5 Â 10 5 m/s on the surface of a glass tube filled with air, [31] which correspond to the surface discharge over a dielectric material under atmospheric pressure [35,36]. When the voltage drops, the discharge disappears at t 6 , but back discharge occurs again at t 7 due to the electric field formed by charges accumulated over the bubble surface.…”

Section: Generation Of Pulsed Discharge Plasmamentioning

confidence: 59%

“…X 2 Π (v = 0) emission lines of OH, respectively. The peak at 656 nm is attributed to a Balmer H-alpha emission [32]. These peaks are strongly observed in argon gas because of its high electron density.…”

Section: Production Of Chemical Species By Discharge Plasmamentioning

confidence: 95%

“…When a pulsed high voltage is applied to the high-voltage electrode in the gas phase, the discharge propagates into the bubble surface from the high-voltage electrode [31,32]. Figure 4 shows typical voltage-current waveforms and flaming photographs of the pulsed discharge generated in an argon bubble, as shown in Figure 2(b) taken by using an intensified CCD camera with an exposure time of 5 ns.…”

Section: Generation Of Pulsed Discharge Plasmamentioning

confidence: 99%

“…Conductivity is the most important parameter for discharge propagation. Generally, the energy efficiency for discharge generation and propagation over a water surface is strongly affected by the conductivity of the water [32,37]. Figure 5 shows the equivalent circuit model [38] of (a) discharge in contact with water using the electrode system shown in Figure 2(b) discharge generated under water using the electrode system shown in Figure 1.…”

Section: Generation Of Pulsed Discharge Plasmamentioning

confidence: 99%

“…Therefore, the discharge length decreases with increasing conductivity. For example, in the case of pulsed discharge generated inside a bubble as shown in Figure 4, the maximum discharge length decreases by 50% by increasing conductivity from 7 μS/cm to 1000 μS/cm [32].…”

Section: Generation Of Pulsed Discharge Plasmamentioning

confidence: 99%

See 4 more Smart Citations

A Novel Wastewater Treatment Method Using Electrical Pulsed Discharge Plasma over a Water Surface

Takahashi¹,

Takaki²,

Satta³

2022

Sewage - Recent Advances, New Perspectives and Applications

Self Cite

View full text Add to dashboard Cite

Electrical pulsed discharge plasma produces various powerful oxidizing agents, such as hydroxyl radicals and ozone, which have high oxidation potential. These species play an important role in the decomposition of persistent organic compounds in wastewater. Because highly concentrated oxidants are directly produced inside the plasma, plasma realizes high-speed wastewater treatment without pretreatment of samples, such as pH adjustment. The pulsed discharge plasma generated over the water surface and inside bubbles is highlighted as a highly efficient method for plasma generation and radical supply into wastewater. In this paper, the physical and chemical properties of the discharge plasma generated over a water surface are described. The decomposition of persistent organic compounds dissolved in wastewater, such as 1,4-dioxane, formic acid, and dichloromethane, by plasma discharge is demonstrated, and their mechanisms are discussed. These persistent compounds, which have strong toxicity and stability, can be efficiently decomposed and removed quickly from solutions by plasma treatment. Furthermore, the treatment of nutrient solutions used in hydroponic systems for plant cultivation is also introduced as a novel application of plasma, and the effects of bacterial inactivation, decomposition of allelochemicals, and improvement in plant growth by plasma are demonstrated.

show abstract