Development of a uniform microwave-induced low-temperature plasma jet array at atmospheric pressure

This paper presents the design of a low-temperature microwave atmospheric-pressure plasma jet array operating at 2.45 GHz, based on a power divider and coaxial transmission-line structures. To expand the discharge area of each individual jet, a hemispherical dielectric block with a diameter of 6 mm was incorporated into the ionization zone of the coaxial plasma source unit. The device can generate four plasma jets at atmospheric pressure with a total microwave input power as low as 55 W. Experimental results demonstrate that increasing the incident power and gas flow rate effectively increases both the length and width of the plasma jets. At a total incident power of 100 W for the array and a gas flow rate of 15 l/min for each jet unit, the jet length reached 9 mm, with a maximum diameter of 7 mm. After 5 min of treatment with one plasma-array unit, the finger-skin temperature was only 35.7 °C. Spectral measurements and sterilization experiments confirmed the high uniformity of the designed plasma jet array. This study offers a potential pathway for industrial applications of large-area microwave atmospheric-pressure plasmas and provides a novel design approach for related devices.