Simulation Designs Of A Compact, Low-power Microwave Plasma Torch And A Cylindrical Microwave Oven Cavity

Microwave energy has been widely used in industrial and agricultural production, medical health, aerospace, life appliances and scientific research. In recent years, using microwave energy, microwave igniter is applied to automobile engine cylinders, which replaces traditional spark plugs, can save energy and reduces exhaust emission. One relatively simple microwave igniter is a quarter-wavelength coaxial resonator. Combining literature and research results and analyzing their strengths and weaknesses, we propose a compact, low-power microwave plasma torch which uses the microwave energy. The device can tune the resonent frequency and can generate the microwave plasma under low power excitation. The microwave oven is now one of important equipment in the household kitchen appliances. Compared with the traditional rectangular microwave oven, the space utilization of the cylindrical cavity is larger. In this paper, we design and simulate a cylindrical cavity microwave oven model to achieve a cylindrical microwave oven with better uniformity and high space utilization. In this paper, the specific content mainly divides into two parts:The first part is to design, machine and experiment the small, low-power microwave plasma torch device. Firstly, the typical quarter-wavelength coaxial resonator was simulated, found out that the electric field at the tip of the inner conductor with 2mm diameter was relatively small, so we designed the outer conductor tip cone structure to improve the electric field, and then optimized the size of the inside and outside of the cavity conductor, coupling structure, size of the aperture, the vent position and tuning structure. After machined the model and tested the resonant frequency, S11 and quality factor of the resonator, it found out that the S11 parameter of the device was less than-12 dB from 2.4 GHz to 2.5 GHz frequency. When the resonant frequency increases, the S11 parameter decreases and the minimum value is about-33 dB at 2.5 GHz frequency, and the quality factor is about 380. Finally, an experimental platform is set up ang result in the microwave plasma torch ignition in the air.The second part is to simulate and design the model of a cylindrical microwave oven cavity. Firstly, the basic module of the magnetron antenna model, the transmission waveguide, the coupling window and a cylindrical cavity were introduced. After optimized the parameters of the cavity radius and height, the position of the coupling window, glass disk radius and used the field calculator to calculate the electric field uniformity, it found out the field uniformity of a single glass of 1000 mL water was not good. So we designed a new model with five cups of water to further study field uniformity and finally found out that the field uniformity in five glasses of 100 mL water changed as the changes of the position of the cups, frequency and phase. Generally speaking, the uniformity of the electric field between the five glasses of water can achieve above 60%. When the rotation angle is 90 o, the uniformity of electric field between the five glasses of water is the best at 72.5%.