Modeling of the propagation of streamers in methane-air mixtures using the 3-group SP$_{3}$ photoionization model

Non-thermal plasma assisted ignition and combustion receives increasing attention recently [e.g., Starikovskaia, J. Phys. D, 39, R265, 2006]. Experimental and numerical work has shown that the application of transient plasma discharges (including the stages of streamer propagation and streamer-to-spark transition) in the ignition of propane-air or methane-air mixtures significantly reduces the ignition delay time [e.g., Pancheshnyi et al., IEEE Trans. Plasma Sci., 34, 2478, 2006; Naidis, J. Phys. D, 40, 4525, 2007]. In this work, we study the propagation of streamers in methane-air mixtures. We have recently developed a photoionization model based on radiative transfer theory, called 3-group SP$_{3}$ model, for the simulation of streamer discharges in air [Bourdon et al., Plasma Sources Sci. Technol. 16, 656, 2007; Liu et al., Appl. Phys. Lett., 91, 211501, 2007]. In this talk, we show it is straightforward to apply the 3-goup SP$_{3}$ model to the simulation of streamers in methane-air mixtures. We report the modeling results on the propagation of streamers in methane-air mixtures and the associated heating of the gas mixtures. We also discuss the effects of addition of methane to air on the dynamics of the streamer.