A High Efficiency Microwave Atmospheric Pressure Air Plasma Jet

A portable microwave atmospheric pressure cold air plasma jet based on a coaxial resonant structure was designed. To lower the plasma excitation power and get higher power efficiency, a tuning structure was added to overcome the manufacturing errors and to compensate for plasma impedance after excitation. The minimum self-excitation power of air by the device was 120 W, and its sustaining power was as low as 50 W. Experiments showed that by tuning the sliding short circuit, the power efficiency of up to 99% in a wide input power range and significantly longer plasma plumes were achieved.