| It is more and more noticed that plasma self-organized pattern can be generated inatmospheric pressure air using liquid as discharge electrode in recent years. It has vastapplication foreground because of simple structure, low cost and convenient operation.The early plasma self-organized patterns have been obtained in atmospheric pressurenon-equilibrium discharge. The work piece to be treated use miniature gas flow or theparallel plate electrode, and mostly the discharge gap is small that limit the shape, sizeand polarity of the electrode. The discharge stability is also susceptible influence.Besides, plasma patterns maintain a strong chemical activity in low gas temperature.Therefore, in recent years, their desirable properties have made them good prospects.In order to realize the discharge mechanism of the pattern formation, the followingwork is done in this paper:1. The three self-organization patterns were formed using a pin-to-water electrodesystem in static atmospheric air driven by an alternating-current (AC) power supply.Electrical characteristics corresponding to the process of the different patternformations in AC (Alternating Current) atmospheric glow discharge were investigatedin Chapter2. In the present work, in order to further understand the characteristic ofthe discharge, we make further research by combining electrical signal and thesynchronous ultrarapid imaging to observe the evolution of the pattern, which isdesirable effect to further study the formation mechanism of self-organization patternin SE-GD (Solution Electrode-Glow Discharge) plasma from the microscopic viewaspect. The channel of discharge is formed at the same time.2. The volt-ampere characteristics of water electrode discharge at several gapdistances were measured, the results show that the area on the water surface for theself-organized patterns were decreased with the increase of the discharge gap.Frequency-power characteristics at various discharge gaps in AC pin-to-waterelectrode atmospheric pressure were discussed, and the necessary conditions for the transformation of the patterns were obtained. The effect of the patterns’ diameters andsolution pH for plasma were discussed. The results show that the pH of solution has agreat influence on the pattern formation. The pH of solution after discharge was alsoinvestigated, and shows that the pH of solution is obviously reduced after discharge,implying that acidic components were produced in the solution. The stable dischargeplasma on the surface of the liquid electrode with a wide-gap separation was obtained,and thus the application scope of the plasma has been extended.3. The optical emission spectrum from200to900nm was collected byspectrometer, besides N2+(391.4nm) line, NO (Aâ†'X)(220280nm) and N2secondpositive band system, O lines at777.2nm and844.6nm were found in the opticalemission spectrum. Spatial distribution of N2molecules and O atoms in atmosphericmetal electrode plasma was studied in Chapter3. The excited processes for O wereexplained, and the spatial distributions for active species were gained because therelative intensities for O lines (777.2nm and844.6nm) were analyzed. The specialprofile of Texc(Excitation Temperature), Tvib(Vibrational Temperature), Trot(RotationTemperature) were studied by emission spectroscopy. The experimental results showthat the electron excitation temperature varied, throughout in the range of5000~25000K, while the vibrational temperature determined from band of N2(5000~9500K) waslower, and the vibrational temperature was about1867.43K.The results of this work have some guides on the mechanism of the liquidelectrode discharge plasma and they are useful for pattern formation. |
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