Insight into discharge mode transition in spatially confined pulsed bubbles-plasma system
Abstract
Bubbles plasma (BP) has emerged as a promising technology for enhancing gas–liquid mass transfer through plasma–liquid interactions, with potential applications in water purification, biomedicine, and chemical synthesis. The discharge mode of BP is a critical factor influencing the mass transfer efficiency of reactive oxygen and nitrogen species (RONS) in plasma-activated water (PAW). This Letter presents a systematic investigation of the discharge mode transition of spatially confined BP driven by microsecond pulses in helium–air mixture under varying gas flow rates. The discharge modes are characterized using both experiment and simulation technologies. Two distinct modes are identified: Mode A, a dual-mode discharge resulting from the synergistic effect of uniform discharge (UD) and spark discharge (SD), and Mode B, a single-mode discharge sustained exclusively by UD without SD involvement. Both modes coexist at flow rates between 500 and 2500 sccm, while only Mode A persists above 3200 sccm. Compared to Mode B, Mode A exhibits a higher emission intensity, Trot, Tvib, and Te, but lower Ne. Meanwhile, to validate the proposed mechanism of mode transition, the concentrations of RONS in PAW and the associated energy efficiency with flow rates are also evaluated. Furthermore, numerical simulations reveal that the mode transition is governed by the interplay between hydrodynamics (airflow distribution) and electrodynamics (electric field distribution), resulting in a significantly enhanced electric field strength in Mode A. These findings provide valuable insights into discharge dynamics of BP and the effective regulation of PAW properties.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (8)
Hezhi Guo
State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, School of Electrical Engineering, Xi'an Jiaotong University , Xi'an, Shanxi 710049,
Zhijie Liu
Zekai Zhang
Key Laboratory for Advanced Materials, Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
Rui Zhu
Qiangwei Wu
State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, School of Electrical Engineering, Xi'an Jiaotong University , Xi'an, Shanxi 710049,
Xin Li
Yuting Gao
State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, School of Electrical Engineering
Bolun Pang
State Key Laboratory of Electrical Insulation and Power Equipment, Centre for Plasma Biomedicine, School of Electrical Engineering, Xi'an Jiaotong University , Xi'an, Shanxi 710049,