Analysis and design of an efficient microwave plasma source by using the principle of variable impedance waveguide

We conducted an analysis and design process to develop a high-frequency electromagnetic thermal plasma source. As part of this endeavor, we designed a standard square waveguide, specifically the WG9A (WR340), operating at a frequency of 2.45 GHz. We implemented two versions of the waveguide, one with a tuner stub and one without, to assess their respective efficiency in producing the desired plasma flare. During the experimentation phase, we employed an electromagnetic wave source with a power output of 1.5 kW. We measured the reflection coefficient (S11) and transmission coefficient (S21) of both waveguides, as well as the temperature of the resulting plasma flame. A thermocouple was employed to measure the maximum temperature achieved, which was recorded at 1,025 °C. Overall, our analysis and experimentation process involved designing the high-frequency electromagnetic thermal plasma source using a standard square waveguide at 2.45 GHz, both with and without a tuner stub. We then assessed the efficiency of the two waveguides in generating the desired plasma flare, taking into account measurements of the reflection and transmission coefficients, along with the temperature of the plasma flame. Our findings indicated a maximum plasma temperature of 1,025 °C, as determined by a thermocouple during the experiment.