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Indexed by:期刊论文

Date of Publication:2008-09-01

Journal:PHYSICS OF PLASMAS

Included Journals:SCIE、EI、Scopus

Volume:15

Issue:9

ISSN No.:1070-664X

Abstract:The discharge in pure helium and the influence of small nitrogen impurities at atmospheric pressure are investigated based on a one-dimensional self-consistent fluid model controlled by a dielectric barrier between two coaxial electrodes. The simulation of the radiofrequency (rf) discharge is based on the one-dimensional continuity equations for electrons, ions, metastable atoms, and molecules, with the much simpler current conservation law replacing the Poisson equation for electric field. Through a computational study of rf atmospheric glow discharges over a wide range of current density, this paper presents evidence of at least two glow discharge modes, namely the alpha mode and the gamma mode. The simulation results show the asymmetry of the discharge set exercises great influence on the discharge mechanisms compared to that with parallel-plane electrodes. It is shown that the particle densities are not uniform in the discharge region but increase gradually from the outer to the inner electrode in both modes. The contrasting dynamic behaviors of the two glow modes are studied. Secondary electron emission strongly influences gas ionization in the gamma mode yet matters little in the alpha mode. (C) 2008 American Institute of Physics.