Comparison of single and concentric split-ring resonator generated microplasmas

Abstract

Microplasmas generated by a single split-ring resonator and a dual concentric split-ring resonator operating at the same frequency are compared. Argon is used as the working gas and held at a pressure of 0.5 Torr. The surface electric fields in the resonators were simulated to gain insight into the behavior of the fields in each device. Double Langmuir probes were used to measure the plasma density and electron temperature in a 2D plane 2 mm above the surface of the resonators. The single and the concentric ring resonators both had a maximum electron temperature in the discharge gap of 2.5 eV. The single and concentric split-ring resonators had the same maximum measured plasma density of 1.19 × 1017 m−3. Plots of the measured properties and comparisons with electric field simulations show the field coupling to the concentric ring and ignition produced in the secondary discharge gap. The concentric ring resonator has more spatially uniform temperature and density distributions relative to the single split-ring resonator.