Nanosecond Plasma Ignition for Improved Performance of an Internal Combustion Engine

Transient plasma, or plasma during a formative true nonequilibrated phase, is studied as an ignition methodology in comparison with traditional spark ignition (2.5-3 ms and 80 mJ) in a single-cylinder gasoline internal combustion engine. Transient plasmas were generated by applying high-voltage pulses that had comparable energy but that were applied for times that were three to four orders of magnitude shorter-85-ns 60-mJ and 20-ns 57-mJ pulses. These created volume-distributed arrays of streamers, which produced electronically excited species during nanosecond time scales. Reductions in ignition delay, higher peak pressure, and increased net heat release ratio relative to conventional spark ignition were observed in these studies. Transient plasma ignition is demonstrated to initiate combustion rapidly, approaching an ideal constant volume cycle; has potential for improving lean combustion operation; is energy efficient; and is potentially useful for gasoline engine emissions reduction.