Study On Characteristics And Modes Of Homogenous Dielectric-barrier Discharge At Atmospheric Pressure

Uniform atmospheric-pressure discharge (APD) controlled by dielectric barriers has attracted considerable attention since its inception because of its advantageous properties for industrial applications. In recently years, experimental and modeling studies on uniform APD have been carried out and some preliminary insights into uniform APD have been obtained. But, in such a spatially extended dissipative system with strong nonlinearity, the discharge behaviors are more complicated than that has been reported. . Many aspects still remain the subject of debate. An in-depth investigation on homogenous APD, especially its complex nonlinear dynamic behaviors, is indispensable to its farther development. In this paper, one-dimensional fluid models for the homogenous barrier discharges at atmospheric pressure have been developed, respectively in helium, helium mixed small impurities and nitrigon. Based on these models, we finish the studies of (a) the behaviors and mechanisms of uniform APD in pure helium including the elementary characteristics of the discharge, the role of helium metastable atoms in the discharge, the forming reasons and properties of multiple-pulse discharge, as well as the operation modes of uniform APD; (b) the influence of small nitrogen impurities on the electrical characteristics and space structures of uniform APD in helium under different discharge modes; (c) the period doubling events and chaotic behavior of homogeneous dielectric-barrier discharge at atmospheric pressure in helium; (d) the plasma dynamics characteristics , dominant mechanisms and structures of uniform APD in nitrogen.The simulaton results show that the homogeneous dielectric-barrier discharge at atmospheric pressure in helium is usually characterized by one current peak per half cycle of the applied voltage. The space structure of this discharge is similar to that of low pressure glow discharge, i.e. there exist four specific regions: the cathode fall; the negative glow; the Faraday dark space; and the positive column. The properties of discharge current are determined by the external conditions. The metastable helium atoms play an important role in the discharge. They mainly produced in the active phase of the discharge and keep its relatively high concentration throughout the discharge. Not only can metastable atom collisions provide seed electrons for discharges, but also produce much more He₂⁺ ions. The behaviors of metastable atoms change with the discharge parameters. A reduction of matestable atom density results in the drop of charged particle densities and causes a qualitative change of discharge patterns. In the case of smaller gap width, multiple current pulses can be formed in each half-cycle of the applied voltage duo to the increases of surface density of the accumulation charges leading to the enhancement of the induced electric field. The development of multiple current peaks usually requires smaller gap width, lower...