Effects of a microwave-induced corona discharge plasma on premixed methane-air flames

A microwave resonator integrated with a floated electrode was used to initiate an additional plasma source to examine the effect on a flame plasma at atmospheric pressure. In the current system, the corona discharge occurred at 200 W of microwave power. The effect of a microwave-induced corona discharge plasma on a flame plasma was investigated using a double Langmuir probe. Through this probe, the electron temperature around the electrode tip was found to be significantly increased by over 350% relative to its original value, and the plasma concentration increased by over 400%. In addition to the effects of the microwave field, a DC field was observed after the plasma discharge, which resulted in a slight bending of the original profile of the ion concentration. Langmuir probe measurements along the flame axis revealed the boundary of effective region of electron acceleration by the microwave field. From the optical emission spectroscopy results measured from the gas where the discharge occurred, the mechanism underlying the flame speed enhancement as well as its application for flame stabilization could be rationalized.