Tunable microwave plasma coaxial resonator

Abstract

We report the design, performance, and characterization of a tunable microwave plasma resonator based on a coaxial transmission line structure operated at atmospheric pressure. The adjustable tuners of the compact device enable over 20 dB enhancement of reflection coefficient by counterbalancing the impedance mismatch. The in situ tuning capability can also neutralize the sudden change in impedance upon plasma discharge, elongating the microwave driven plasma plume. It is observed that the fine adjustment of two small bolts can maintain a high device efficiency up to 96% with plasma load impedance, and a wide operation range can be covered by a single device.