title: [Influence of Argon Content on Plasma Temperature of Single Filament in Dielectric Barrier Discharge].
abstract: The single filament (also referred to as monofilament) which composed of two parts including the center spot and the outer halo is observed and researched for the first time in dielectric barrier discharge, which filled with gas-mixture of argon and air. The pictures taken from the experiment show that the diameter of the monofilament decreases with the increasing of the content of the argon in the argon-air mixture, and at the same time there is an obvious difference on brightness between the center spot and the outer halo. All of these phenomenons suggest that the center spot and the outer halo are probably in different plasma state. The micro character of the center spot and the outer halo is researched seriously in the experiment by the time-resolved measurement with optical method. Three plasma temperatures of the center spot and the outer halo in single filament in different argon content are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band (C3 π(u) --> B3 πg) are measured, from which the molecule vibrational temperature of the center spot and the outer halo are calculated. Based on the relative intensity of the N2 line at 391.4 nm and the N2 line at 394. 1 nm, the changing relationship of the average electron energy of the center spot and the outer halo with argon content is investigated. The spectral lines of Ar I 763.2 nm (2P6 --> 1S5) and 772.077 nm (2P2 --> 1S3) are chosen to estimate electron excitation temperature of the center spot and the outer halo by the relative intensity ratio method. The results show that the optical signal corresponding to the first lasge pulse is the center spot, whose signal intensity is a litter weaker; and the optical signal containing the whole pulse is the outer halo, whose signal intensity is stronger. The three plasma temperatures including the molecule vibrational temperature, average electron energy and electron excitation temperature of the outer halo are higher than those of the spot at the same argon content without exception. In addition, the molecule vibrational temperature of the center spot and the outer halo decrease with the argon content increases from 30% to 50%, while on the other hand, electron excitation temperature and average electron energy are decrease gradually.
authors.forename: Hong-yan
authors.initials: HY
authors.lastname: Fu
authors.forename: Li-fang
authors.initials: LF
authors.lastname: Dong
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao