Propagation of positive discharges in an air bubble having an embedded water droplet

Journal Article · Tue Jan 05 00:00:00 EST 2021 · Plasma Sources Science and Technology

DOI:https://doi.org/10.1088/1361-6595/abc830· OSTI ID:2331478

Ning, Wenjun ^[1]; Lai, Janis ^[2]; Kruszelnicki, Juliusz ^[2]; Foster, John E. ^[2]; Dai, Dong ^[3]; Kushner, Mark J. ^[2]

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1. Sichuan Univ., Chengdu (China); Univ. of Michigan, Ann Arbor, MI (United States); University of Michigan
2. Univ. of Michigan, Ann Arbor, MI (United States)
3. South China Univ. of Technology (SCUT), Guangzhou (China)

Low temperature plasmas generated inside gas bubbles immersed in water is an effective method of rapidly transferring plasma generated reactive species to the water for applications in biomedicine, agriculture and environment. Reactive species are generally produced in the gas phase plasma and then solvate into the liquid. The large surface-to-volume ratio (SVR) of the bubble accelerates this process. In generating bubbles in water, aerosols and droplets are also contained within the bubble. These droplets also have a large SVR and so can be rapidly plasma activated. However, the presence of the droplets can also impact the propagation of the plasma in the bubble. In this paper, results are discussed from computational and experimental investigations of the formation and evolution of discharges in an air bubble immersed in water with an embedded water droplet. The computations were performed with a two-dimensional plasma hydrodynamics model. Experiments were performed with a quasi-2D bubble apparatus. In bubbles having a droplet, a plasma filament typically bridges from the powered electrode to the droplet, and then from the droplet to the bubble surface. A surface-hugging streamer also occurs on the inner bubble surface and on the surface of the droplet. Both surface streamers result in part from surface charge accumulation and can dominate the formation of reactive species that transport into the droplet. Increasing droplet conductivity suppresses propagation of the surface discharge and leads to a lower density of aqueous reactive species. Increasing conductivity of the surrounding water does not change the overall structure of the discharge but does slightly elevate the discharge intensity. Finally, the size and shape of the embedded droplet can significantly affect the formation and propagation of the streamer.

• Research Organization: Univ. of Michigan, Ann Arbor, MI (United States)
• Sponsoring Organization: National Nature Science Foundation of China (NSFC); National Science Foundation (NSF); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: SC0001939; SC0020232
• OSTI ID: 2331478
• Alternate ID(s): OSTI ID: 1850778
• Journal Information: Plasma Sources Science and Technology, Journal Name: Plasma Sources Science and Technology Journal Issue: 1 Vol. 30; ISSN 0963-0252
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

2D fluid modelling
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
bubble
droplet
plasma-water interactions