Characteristic Of Argon Plasma Jet In Needle-Ring Dielectric Barrier Discharge

Atmospheric pressure plasma jet is a new low-temperature plasma technology developed in recent years. Plasma jet has good application prospect in material processing, biomedical engineering, plasma chemical industry and other fields due to its unique advantages such as absence of vacuum system, low gas temperature and flexibility, etc. Compared with helium, argon with a low cost is more suitable for large-scale promotion in practical application. In this thesis, the characteristics of plasma jet in argon needle-to-ring dielectric barrier discharge are studied experimentally.Firstly, the influence of operating conditions such as the applied voltage, argon flow rate, gas component and the needle radius of curvature on the plasma jet characteristics including the length of jet, the current and the dissipated power has been investigated experimentally. The results show that the corona discharge and dielectric barrier discharge exist simultaneously in needle-to-ring configuration. The length and power of jet are stable at low voltage but increasing at high voltage. The discharge turns to multiple pulse when rising the applied voltage. The argon flow provides the discharge channel for plasma jet developing, no matter how the channel curves. There is an optimal proportion of argonhelium mixture to generate stable and longer plasma jet. Then, the time-resolved development of plasma jet and its spectrum are investigated. It is demonstrated that there are two discharge modes, relating to the strength of electric field downstream. The formation and development of plasma jet is due to the electric field caused by the positive charges accumulating in space near the instantaneous cathode. The process is similar to the positive corona discharge.