Study On Syntonic Problem And Charges Deposited In Dielectric Layers Of DBD Device

Large-volume and high-density non-equilibrium plasma generated by dielectric barrier discharge (DBD) at atmospheric pressure has been paid more attention owing to its wide application in some fields such as plasma chemistry engineering, material surface treatment and environmental engineering, etc. However the study on DBD is done behind time, many problems on evolution mechanism of DBD and its application process are not understood thoroughly, which limited the development of DBD. In this paper, the syntonic of DBD device and the effect of the charges deposited in dielectric layers are studied experimentally based on "Studies on the Ionization of Gas Molecule Using Ultra-Strong Electrical Field Discharge and Its Applications"(No: 69871002) supported by National Natural Science Foundation of China, which supply the experimental basis for optimizing system parameters and improving the characteristic of DBD. The main results of the study are shown as following:1.There is the syntonic phenomenon in DBD system, which results from the leak inductance of the transformer (LIT) and the equivalent capacitance of the dielectric layer (ECDL). Discharge characteristic will descend when the system works at above the syntonic frequency. In order to get better discharge characteristic at higher frequency, LIT and ECDL must be reduced and the intrinsic frequency of the system must be higher than the working frequency.2.The system assumes resistance when it is working under the condition of resonance, so the supply voltage can be coupled to the discharge gap of DBD directly; the equivalent resistance of DBD plasma can be measured according to the characteristic of resistance, which can diagnose the evolution of DBD plasmas.3.Micro-discharge is one of the main characteristics of DBD, in which excitation and ionization of the media gas just occur. With the effect of the applied electric field, charges ionized which produce radial field can deposit in the dielectric layer, which in turn react to the discharge charges and thus influence the evolution processing of DBD plasma. Some factors can affect greatly the effect of chargesdeposited in layer, such as applied voltage and frequency, dielectric material, DBD configuration and media gas, etc. Using high-frequency power supply, narrow-gap, thin dielectric layer of high-purity a -Al2O3 can improve the effect of charges deposited in layer, and help plasma reaction proceed to the direction of target product.