A high efficiency low-temperature microwave-driven atmospheric pressure plasma jet

The design, performance, and characteristics of a low-temperature microwave-driven atmospheric pressure plasma jet (MAPPJ) are presented. The MAPPJ is based on a complex coaxial transmission line structure, and the gas is discharged by a continuous-wave microwave. By inputting two channel gas through inner and outer coaxial transmission lines, respectively, the gas flow can be restricted and the plasma jet open to atmospheric air could be long and straight without quartz tube. A 28.6 mm long straight low-temperature plasma jet is observed in the experiment. This MAPPJ device shows high efficiency in a wide operation range, and a maximum efficiency of 89.6% is measured in the experiment without a microwave matching network. This approach can be an initiation toward the commercialization of low-temperature MAPPJs.