[Study on Spectral Characteristics of Filaments in Three Layers Gas Gap in Dielectric Barrier Discharge].

By optical emission spectrum, we report on the first investigation on the spectral characteristics of filaments in three layers gas gap in dielectric barrier discharge, which filled with gas-mixture of argon and air. The filaments are generated in 1 mm gas gap, 4 mm gas gap and 2 mm gas gap, respectively. With previous single layers gas gap or double layers gas gap of the filaments are very different in terms of spectral characteristics. The emission spectra of the N2 second positive band (C(3)Π(u)→B(3)Π(g))are measured, from which the molecule vibrational temperature of the filaments which generated in different gas gap are calculated. Based on the relative intensity of the line at 391.4 nm and the N2 line at 394.1 nm, the electron average energy of the filaments which generated in different gas gap are investigated. Increasing the content of argon, the change of the molecule vibrational temperature and the electron average energy of the filaments are investigated. It is found the ascending order of the molecule vibrational temperature in the same argon content is: 2 mm gas gap, 1 mm gas gap and 4 mm gas gap. However the ascending order of the electron average energy in the same argon content is: 4 mm gas gap, 2 mm gas gap and 1 mm gas gap. The molecule vibrational temperature and the electron average energy of the filaments decrease with the argon content increasing.

[Study on Hexagonal Super-Lattice Pattern with Light Spot and Dim Spot in Dielectric Barrier Discharge by Optical Emission Spectra].

The hexagonal super-lattice pattern composed of the light spot and the dim spot is firstly observed and investigated in the discharge of gas mixture of air and argon by using the dielectric barrier discharge device with double water electrodes. It is found that the dim spot is located at the center of its surrounding three light spots by observing the discharge image. Obviously, the brightness of the light spot and the dim spot are different, which indicates that the plasma states of the light spot and the dim spot may be different. The optical emission spectrum method is used to further study the several plasma parameters of the light spot and the dim spot in different argon content. The emission spectra of the N2 second positive band (C³IIu --> B³IIg) are measured, from which the molecule vibration temperatures of the light spot and the dim spot are calculated. Based on the relative intensity ratio of the line at 391.4 nm and the N2 line at 394.1 nm, the average electron energies of the light spot and the dim spot are investigated. The broadening of spectral line 696.57 nm (2P2-1S5) is used to study the electron densities of the light spot and the dim spot. The experiment shows that the molecule vibration temperature, average electron energy and the electron density of the dim spot are higher than those of the light spot in the same argon content. The molecule vibration temperature and electron density of the light spot and dim spot increase with the argon content increasing from 70% to 95%, while average electron energies of the light spot and dim spot decrease gradually. The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs). The surface discharge induced by the volume discharge (VD) has the decisive effect on the formation of the dim spot. The experiment above plays an important role in studying the formation mechanism of the hexagonal super-lattice pattern with light spot and dim spot. In addition, the studies exert influences on the application of surface discharge and volume discharge in different fields.

[Study on Square Super-Lattice Pattern with Surface Discharge in Dielectric Barrier Discharge by Optical Emission Spectra].

Square super-lattice pattern with surface discharge consisting of central spots and dim spots is firstly observed in the mixture of argon and air by using a dielectric barrier discharge device with water electrodes. By observing the image, it is found that the central spot is located at the centriod of its surrounding four dim spots. The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs). The brightness of the central spot and is quite different from that of the dim spot, which indicates that the plasma states of the central spot and the dim spot may be differentiated. The optical emission spectrum method is used to further study the several plasma parameters of the central spot and the dim spot in different argon content. The emission spectra of the N2 second positive band (C³IIu --> B³ IIg) are measured, from which the molecule vibration temperatures of the central spot and the dim spot are calculated respectively. The broadening of spectral line 696.57 nm (2P2-->1S5) is used to study the electron densities of the central spot and the dim spot. It is found that the molecule vibration temperature and electron density of the dim spot are higher than those of the central spot in the same argon content The molecule vibration temperature and electron density of the central spot and the dim spot increase with the argon content increasing from 90% to 99.9%. The surface discharge induced by the volume discharge (VD) has the determinative effect on the formation of the dim spot The experimental results above play an important role in studying the formation mechanism of surface discharg&of square super-lattice pattern with surface discharge. In addition, the studies exert an influence on the application of surface discharge and volume discharge in different fields.

[Study on the Plasma Parameters of the Spot-Halo Hexagon Pattern with Optical Emission Spectrum].

The spot-halo hexagon pattern consisted of the center spot and hexagon halo in dielectric barrier discharge is researched, which filled with gas-mixture of argon and air. The pictures taken from the experiment shows that there is an obvious difference on brightness between the center spot and hexagon halo. All of these phenomena suggest that the center spot and hexagon halo are probably in different plasma state. The plasma parameters of the center spot and hexagon halo in the spot-halo hexagon pattern as a function of gas pressure are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band(C3Πu→B3Πg)are measured, from which the molecule vibrational temperature of the center spot and hexagon halo are calculated. Based on the relative intensity of the line at 391.4 nm and the N2 line at 394.1 nm, the change of the electron average energy of the center spot and hexagon halo as a function of gas pressure is investigated. The electron density is studied by using the broadening of the spectral line 696.5 nm. It is found that the main chart of the spot-halo hexagon pattern is the argon content from 60% to 75% and the pressure from 30 to 46 kPa. The molecule vibrational temperature and electron average energy of the hexagon halo are higher than those of the center spot at the same pressure. As the pressure gradually increased from 30 to 46 kPa, the molecule vibrational temperature and electron average energy of the center spot and hexagon halo are increased, too. The broadening of the spectral line of the hexagon halo is bigger than the center spot at the same pressure, which increases with the gas pressure increasing. It indicates that the electron density increases with gas pressure increasing. The different plasma state of the center spot and hexagon halo show that the different formations mechanism of them. It is found that there are volume discharges firstly and then comes surface discharges with e high speed camera.