Improving the Power Efficiency of a Microwave Plasma Source by Using the Principle of a Variable-Impedance Waveguide

Abstract

Microwave plasma sources are used in various applications, but inefficiency can limit their usefulness. Researchers have investigated a new approach with which to improve efficiency by using a waveguide with a special tuner. A standard waveguide was compared to one equipped with a stub tuner, which allows for the fine-tuning of the electrical properties. The experiment used a frequency of 2.45 GHz and tested input powers of 1 kW and 1.5 kW. Experiments showed that waveguides with tuners transferred power more efficiently, with fewer reflected and more transmitted microwaves. While peak temperatures remained similar, the tuned waveguide produced a hotter plasma flame (30–60 °C) at the same distance. Notably, increasing the input power further boosted the flame temperature by 300 °C. These findings suggest that stub tuners can significantly improve the efficiency of microwave plasma sources. This paves the way for more efficient plasma generation technologies and potentially allows for applications requiring even higher power.