Study On A New Plasma-jet Generator Excited By Surface Waves

Microwave plasma jet has broad prospects in application due to its unique characteristics, such as high concentration active particles, pollution free technology and low cost. Microwave plasma jet can discharge under low and high pressure with low incident power, and the discharge process is safe with no high voltage power. Thence, MPJ has various application value in industrial purposes, such as plasma ignition, plasma etching, material surface treatment and air purification.This thesis discusses the development work of low power microwave plasma jet based on the surface wave plasma polaritons(SPPs) mainly include four aspects as discharge mechanism, simulation analysis, experiment research, parameter diagnosis and engineering application. The idiographic work is as follows:(1)Microwave transmit in the waveguide with the mode of TE10 while the SPPs between the excited antenna and quartz tube is TM mode as the process of wave mode conversion at resonant point. Then, the low-power MPJ is produced from gas ionization excited by local enhanced electric field of SPPs.(2)The fluid simulation research on the discharge process is built with COMSOL software, and simulate on the electron density, electron temperature and electric field distribution. We found that discharge arrives at its stable states at about 500.0ns. We also build the spiral antenna model to verify important role of the new antenna structure on the enhancement of electric field.(3)Changing the experimental conditions, we study the impact of gas, gas pressure, gas flow, incident power and excited antenna structure on the plasma jet. Design new structure of metal antenna, we study the low power MPJ. The experiment device may discharge with 5W for various gases. The unique structure of internal metal antenna with an adjusting screw-pitch gauge is convenient to control plasma discharge at different locations for various gases, MPJ can be operated at wide pressure range with low incident power. Regulating the position of the metal antenna and the flow rate, a plasma jet with a length of 7.5 cm is generated 50-cm away from the hole of the waveguide when incident power reaches 50 W.(4)Ava Spec-3648 fiber optic spectrometer is adopt to diagnose the discharge particle and the change of light intensity of the plasma jet under different pressure. Double probe diagnostic system is designed to diagnose the plasma parameters in low pressure and study the influence of incident power and gas flow on the plasma density and jet length.(5)We design an air cleaning unit and make experimental research on cigarette smoke cleaning using the active material and high-energy particle in the plasma jet. Experimental results show that MPJ has an obvious effect of purification the cigarette smoke and the active material may keep air clean for long.