Images of Atmospheric-Pressure Microplasmas Produced by Continuous 2.45-GHz Excitation

This paper presents an imaging analysis of stable microplasmas produced in air, argon, and helium at atmospheric pressure, using a continuous microwave (2.45-GHz) excitation. The source is a linear-type resonator similar to a microstrip line. The microplasma develops within the 50-200-μm gap created between two metal electrodes (6 mm in length), placed at the open end of the transmission line. Images allow visualizing some of the plasma features and estimating the plasma volumes and, hence, the maximum power density coupled to the plasma.