Numerical modeling of plasma assisted ignition of CH4/O2/He mixture by the nanosecond repetitive pulsed surface dielectric barrier discharge

A nanosecond repetitive pulsed surface dielectric barrier discharge (NRP-SDBD) is a promising method for generation of non-equilibrium plasma with more kinetic activity. This paper presents numerical studies on the effects of pulse repetition frequency (PRF) on low temperature ignition of lean and stoichiometric CH4/O2/He mixture in NRP-SDBD plasma. A skeletal plasma kinetics mechanism is primary developed and calibrated, to mitigate the computational loads of modeling SDBD discharge by the two-dimensional plasma solver PASSKEy coupled with Poisson's equation. The discharge current was well predicted, meanwhile the sequential and spatial reduced electric field (E/N) is revealed as the ionization wave propagates forward. Special attention is placed on time-evolution of electric field strength used as inputs in simulation of plasma assisted ignition (PAI) conducted by zero-dimensional ZDPlasKin-CHEMKIN code. The principle of PAI on lean and stoichiometric CH4/O2/He mixture via varied PRF is analyzed in details from view of plasma kinetics and chemical kinetics. Ultimately, the important role of plasma active species O, O(1D), O2(a1 Delta g) on promoting ignition chain reactions is highlighted. It is also concluded that high PRF is beneficial for the accumulation of short lifetime species such as CH4(v13) and O(1D), which participate in the formation of important intermediate CH3.