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Title: Gas breakdown mechanism in pulse-modulated asymmetric ratio frequency dielectric barrier discharges

The gas breakdown mechanisms, especially the roles of metastable species in atmospheric pressure pulse-modulated ratio frequency barrier discharges with co-axial cylindrical electrodes, were studied numerically using a one dimensional self-consistent fluid model. Simulation results showed that in low duty cycle cases, the electrons generated from the channels associated with metastable species played a more important role in initializing next breakdown than the direct ionization of helium atoms of electronic grounded states by electron-impact. In order to quantitatively evaluate the contribution to the discharge by the metastables, we defined a “characteristic time” and examined how the value varied with the gap distance and the electrode asymmetry. The results indicated that the lifetime of the metastable species (including He*and He{sub 2}{sup *}) was much longer than that of the pulse-on period and as effective sources of producing electrons they lasted over a period up to millisecond. When the ratio of the outer radius to the inner radius of the cylindrical electrodes was far bigger than one, it was found that the metastables distributed mainly in a cylindrical region around the inner electrode. When the ratio decreased as the inner electrode moved outward, the density of metastables in the discharge region near themore » outer electrode became gradually noticeable. As the discharging gap continued to decrease, the two hill-shaped distributions gradually merged to one big hill. When the discharge spacing was fixed, asymmetric electrodes facilitated the discharge.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [3]
  1. School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116023 (China)
  2. Department of Mechanical Sciences and Engineering, Tokyo Institute of Technology, Tokyo 152-8550 (Japan)
  3. Southwestern Institute of Physics, Chengdu 610041 (China)
Publication Date:
OSTI Identifier:
22303803
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASYMMETRY; ATMOSPHERIC PRESSURE; BREAKDOWN; CYLINDRICAL CONFIGURATION; DISTANCE; DISTRIBUTION; ELECTRODES; ELECTRONS; HELIUM; IONIZATION; PULSES; SIMULATION