The Research Of The Radial Expansibility Of Microdischarge Channel And The Uniformity Of Discharge

Dielectric barrier discharge (DBD) can produce the non-thermal equilibrium plasma. Up to now, DBD can be widely applied to the field of electrical insulating material surface modification, sterilization, CO2 laser, the plasma display panel, ozone generation and so on. By the particle simulation of the uniform DBD and experimental study about DBD radial expansibility, the paper has research the DBD radial expansibility and uniformity.Firstly, build the simple model for the particle simulation and simulate numerically the process of electron avalanche growth in uniform gas. The results indicate, in order to produce uniform discharge in air atmospheric pressure, it needs to slow down the development of avalanche growth and restrain the formation of streamer. The space charges have a great influence on electric field near head of the electron avalanche. When the distances between the two electron avalanches is larger than 400μm, the space charges have a small influence on axial electric field of midperpendicular, also in the critical position of the electron avalanche transforming into streamer, the axial electric field is substantially smaller than the external initial electric field. Consequently, the two electron avalanche can develop independently when the distance between the two electron avalanches is larger than 400μm.Secondly,according to characteristics of DBD, build the model for the particle simulation considering space charges and deposition charges, do the particle simulation of uniform DBD(Towsend discharge pattern). It shows that it can slow down electron avalanche transforming into streamer to produce uniform discharge by controlling the influence of space charges and deposition charges adjusting external conditions. There are three situations in the process of two initial electron avalanche growth simultaneously in DBD, such as merged electron avalanche, two electron avalanche growth simultaneously, unmerged electron avalanche– streamer. Based on this, the paper proposes the"mergeing degree"C of electron avalanche to describle the conditions of realizing the uniform DBD. We also find that in the calculation, if without considering the deposition charges, the two electron avalanches are mutually exclusive, which is traditional standpoint, but if the quantity of deposition charges is appropriate, the two electron avalanche have an attractive tendency. The new phenomenon needs to be confirmed by experiments.Finally, using spherical electrode with radius of different curvature, do the experimental research on DBD radial expansibility. Observe the experiment phenomena is"dark ring in the middle, bright ring on the edge".The phenomena is connected with the length of gas, air pressure, voltage and frequency. The pattern of dark ring in the central region is uniform discharge, thus the pattern of bright ring on the edge is filamentary discharge. And the before-mentioned particle simulation of the uniform DBD can explain the experimental phenomena.