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Indexed by:期刊论文

Date of Publication:2017-03-28

Journal:JOURNAL OF APPLIED PHYSICS

Included Journals:SCIE、EI

Volume:121

Issue:20

ISSN No.:0021-8979

Abstract:A two-dimensional self-consistent fluid model and the experimental diagnostic are employed to investigate the dependencies of species concentrations on the gas proportion in the capacitive N-2/Ar discharges operated at 60MHz, 50 Pa, and 140 W. The results indicate that the N-2/Ar proportion has a considerable impact on the species densities. As the N-2 fraction increases, the electron density, as well as the Ar+ and Ar-m densities, decreases remarkably. On the contrary, the N-2(+) density is demonstrated to increase monotonically with the N-2 fraction. Moreover, the N density is observed to increase significantly with the N-2 fraction at the N-2 fractions below 40%, beyond which it decreases slightly. The electrons are primarily generated via the electron impact ionization of the feed gases. The electron impact ionization of Ar essentially determines the Ar+ density. For the N-2(+) production, the charge transition process between the Ar+ ions and the feed gas N-2 dominates at low N-2 fraction, while the electron impact ionization of N-2 plays the more important role at high N-2 fraction. At any gas mixtures, more than 60% Ar-m atoms are generated through the radiative decay process from Ar(4p). The dissociation of the feed gas N-2 by the excited Ar atoms and by the electrons is responsible for the N formation at low N-2 fraction and high N-2 fraction, respectively. To validate the simulation results, the floating double probe and the optical emission spectroscopy are employed to measure the total positive ion density and the emission intensity originating from Ar(4p) transitions, respectively. The results from the simulation show a qualitative agreement with that from the experiment, which indicates the reliable model. Published by AIP Publishing.