Visual features of microwave ignition of methane-air mixture in a constant volume cylinder

In this paper, the visual features of microwave ignition process were investigated. To realize microwave ignition under high pressure, a 2.45 GHz cylinder microwave resonator was designed. The electric field in the resonator and the quality factor were theoretically calculated. A needle-like coupling antenna was introduced to further enhance the maximum electric field to ensure the reliability of discharge. We ignited stoichiometric methane-air mixture at 10 bars by a 2 ms, 1 kW, 2.45 GHz microwave pulse. The photography images and pressure history of the ignition were obtained and analyzed. These results were compared with spark plug ignition under identical conditions.