Characteristic Study On The Microwave Plasma Torch Stabilized By Two Gas Flows At Atmospheric Pressure And Its Preliminary Applications

Atmospheric pressure (AP) plasma exhibits advantages in reducing operating cost and carrying out various material treatments compared with low-pressure plasma technology. Microwave discharges are used in an increasing number of applications including surface treatment (e.g., deposition, nitriding, etching), light sources, and spectrochemical analysis. In this article, we have used two types of microwave discharge:a microwave plasma torch and a surface wave plasma discharge.In order to achieve the stably controlling of the atmospheric-pressure microwave plasma torch, the in-depth experimental research has been done about issue of the impedance matching and it is found that the position of plunger on the end of applicator of the microwave waveguide and the arrangements of the gas flow field play a crucial role in the stability of the microwave plasma discharge. A suitable adjustment of the position of plunger can make the maximum of the standing wave located at the position of the strongest field strength in the applicator, thereby the gas is more likely to be struck. And the combining arrangement of the rotating and vertical gas flow can inhibits the occurrence of filamentation effectively.In this work, an atmospheric pressure nonequilibrium microwave Ar/O2plasma torch was used to implement the cleaning process of aluminum surface contaminated by organic compound. The various excited particles generated in the discharge plasma with high kinetic energy bombard the substrate and react with the molecules of the organic compounds. The water contact angles of the aluminum panel were measured by the contact angle meter. It is experimentally confirmed that the effective cleaning and modification of metal surfaces has been accomplished.A pulse-modulated nonequilibrium atmospheric-pressure microwave argon plasma discharge is generated by mean of preionization discharge of a single electrode plasma jet driven by a kilohertz power supply of50kHz. It is found that the Saha-like balance dominates the electron induced excitation process with the electron temperature modified by kilohertz power supply. The characteristics of atmospheric-pressure microwave surface wave plasma are studied with respect to its modulating effect by measuring the excitation temperature and gas temperature. In the study of pulse-modulated surface microwave plasma jet, the almost linear increasing tendencies of both temperatures are approximately proportional to the average input power and its DR value. However, the increasing ratio of mean gas temperature is much larger than that of the mean excitation temperature or electron temperature, which shows that the pulse modulation can alter the equilibrium deviation appreciably and it is possible to get a low gas temperature and high excitation temperature or electron temperature during on-time of pulse modulation by combination of the output power of microwave supply and its DR value.