Design Of The Composite Antenna Of A Microwave Jet Device

Atmospheric microwave plasma has wide application prospects due to it has many good characteristics, such as high electron temperature, high electron density, no electrode contamination and simplified production setup. Atmospheric microwave plasma is suitable for industrial production, it has been widely used in surface treatment, materials synthesis, medical sterilization, environmental protection,and so on. However, the microwave plasma discharge at atmospheric pressure is very difficult and requires really high incident microwave power.A novel microwave plasma jet device based on surface plasmon polaritons is designed in this paper, this device can produce argon discharge at atmospheric pressure with a very low power. The finite element software COMSOL is used to model the jet device and optimize the microwave energy coupled component, the engineering design and discharge experiments are also completed. Specific optimization work includes: depending on tip discharge principle, the bottom of the antenna is sharpened, which greatly improves the microwave field in the discharge tube. Then, the antenna is designed to folding antenna with double tips, producing a greater volume of plasma and improving the utilization of microwave energy. The influence between the radius and the position in the discharge tube of the antenna and the electric field in the tube has been explored, and the best optimization method is obtained. The improved microwave plasma jet can produce an argon discharge under atmosphere with a microwave power of 10 W. When the microwave power is 50 W, the jet produces a 30 cm long plasma jet under low-pressure. Compared with the traditional microwave jet device, the new design of microwave energy jet device has better coupled of energy, discharge ability is stronger, and the utilization of energy is higher.In this paper, the composite antenna and the discharge tube of the jet device is subversivly designed, which is the most creative work in this article, the practical applications on the industrial of the jet device have become more widespread. On the one hand, the traditional cylindrical metal antenna is transformed to spiral metal antenna, the discharge result is better, and a new discharge mode is realized – the remote control discharge. An argon jet discharge is produced 60 cm away from the microwave waveguide notch under the atmospheric environment. On the other hand, the traditional cylindrical discharge tube is transformed to a new bottle shaped discharge tube. The discharge section radius is enlarged from 2 mm to 5 cm, and it realizes a large area discharge in the discharge tube. The achievements made in this article provide a useful reference for low power, high efficiency, large area plasma treatment process of industrial applications.