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Plasma Sci. Technol. ›› 2018, Vol. 20 ›› Issue (7): 075403.doi: 10.1088/2058-6272/aab4f2

• Low Temperature Plasma • Previous Articles     Next Articles

Physicochemical properties of the AC-excited helium discharges using a water electrode

Hafiz Imran Ahmad QAZI1, Yiying XIN (辛怡颖)2, Muhammad Ajmal KHAN1, Heping LI (李和平)1,3, Lu ZHOU (周律)2 and Chengyu BAO (包成玉)1   


  1. 1 Department of Engineering Physics, Tsinghua University, Beijing 100084, People’s Republic of China
    2 School of Environment, Tsinghua University, Beijing 100084, People’s Republic of China
  • Received:2017-11-29 Published:2018-03-07
  • Supported by:

    This work has been supported by the Major Science and Technology Program for Water Pollution Control and Treatment (No. 2014ZX07215-001) and partly by National Natural Science Foundation of China (Nos. 11475103, 51578309).


In this paper, the AC-excited helium discharges generated between the powered needle electrode enclosed in a conical quartz tube and the grounded de-ionized water electrode are investigated. The current and voltage waveforms exhibit a transition from the glow-like to streamer-like mode discharges, which forms a stable cone-shaped structure at the gas–liquid interface. In this region, the air and water vapor diffusion initiate various physical–chemical processes leading to substantial changes of the primary species emission intensities (e.g., OH, N2, NO, and O) and the rotational temperatures. The experimentally measured rotational temperature at the gas–liquid interface is 870 K from the N2(C–B) band with a power input of 26 W. With the prolongation of the discharge time, significant changes in the discharge voltage and current, discharge emission patterns, instantaneous concentrations of the secondary species (e.g., H2O2 and ) in the liquid phase, pH values and electrical conductivities of the liquids are observed experimentally. The present study is helpful for deepening the understandings to the basic physical–chemical processes in the discharges in contact with liquids, especially to those occurring in the vicinity of the gas–liquid interface, and also for promoting existing and potential applications of such type of discharges in the fields of environmental protection, biomedicine, agriculture, and so on.

Key words: solution plasma, gas–liquid interface, wastewater treatment, biomedical science and agriculture applications