Microwave plasma ignition process of methane and air mixture under high pressure

Since the 21st century, searching for new ways and approaches to improve efficiency and to reduce exhaust gases of internal combustion engines has never been ceased. One of these innovation technologies is microwave plasma ignition. And this paper describes an applicable method for microwave plasma ignition. This method was realized in a metal closed cavity which imitates the combustion chamber in an internal combustion engine. The mixture of methane and air was successfully ignited by microwave plasma under 5~10 bar. The igniting process was recorded by a high-speed CCD camera and the curve of pressure was synchronously measured. These results were compared with the ignition process excited by a spark plug. The results show that the combustion ignited by microwave plasma is much more vigorous than by spark plug. The peak of pressure is higher in microwave plasma ignition. But the time characteristics of pressure curves show little difference between microwave plasma ignition and spark plug ignition.