A low power microwave room-temperature air plasma jet at atmospheric pressure

An atmospheric pressure low power microwave-induced air plasma source at 2.45 GHz is presented in this Letter. The device was capable of self-igniting air and generating plasma with only 50 W microwave input power and without any extra trigger. Its sustaining power was as low as 10 W, and the gas temperature of plasma tail flame measured by a fiber optic thermometer was about 32 °C. Spectroscopic measurements showed strong OH(A2Σ+→X2Π) bands at 306–310 nm and oxygen atomic lines OI (3p5P → 3s5S) at 777.1 nm and OI (3p3P → 3s3S) at 844.6 nm. NO−γ(A2Σ+→X2Πr) from 200 to 300 nm was also detected in this air plasma jet. This portable plasma apparatus offers potential for air plasma applications in the biomedical fields.