Structure Of Dielectric Barrier Glow Discharge And Its Formation Mechanism

Dielectric barrier discharge (DBD) is not only one of the popular systems generatingnon-equilibrium plasma but also an excellent nonlinear dissipative system to studyself-organized patterns. The investigations of discharge structure in glow DBDs lead toimportant insight concerning the theoretical understanding of discharge plasma physics anduniform discharge formation at atmospheric pressure as well as the industrial applications.In this dissertation, various DBD structures depending on the discharge conditions and thespatio-temporal evolutions of the discharge structures are investigated. The key roleinfluencing the discharge structures are discussed.Firstly, the DBD structures were investigated experimentally under differentconditions and various patterns were observed. The dependence of DBD structure on thedischarge conditions including the driving voltage, the frequency, the duty ratio of powersource, the gas pressure, the applied magnetic field, etc., were obtained.Then, the discharge process of stable DBD in a current pulse is obtained by both theexperiment and two-dimensional (2D) modeling based on the drift-diffusion approximation.For a stable glow DBD, the discharge starts from the position where there are more spaceand surface charges. A reversed discharge phase appears during the current decay. Thedischarge cannot cover completely the entire electrode surface, but remains a border ofweak discharge according to the boundary effect.Finally, the effect of the space charge and the surface charge on the structureformation of glow DBDs were analyzed by the2D fluid model.. The non-uniform spacecharge or surface charge can induce a kind of activation-inhibition effect which depends onthe fluctuation of charge density and the voltage. The activation-inhibition effect can showthrough only in a period during afterglow that defines a critical lower and upper frequencyfor the fluctuation of electrons to be enhanced. It is suggested that the space charge plays animportant role in the transition between the patterned and uniform DBD, while the surfacecharge has only a supplementary effect. The discharge conditions such as the voltage, thefrequency, the gas pressure, the boundary of the electrode and the magnetic field influencethe activation-inhibition effect and hence the DBD structure.