The effect of the ionic wind on a premixed methane-air flame under a DC electric field is studied via mapping of the ion density with Langmuir probes. Ion densities were observed to increase near the burner with increasing electrode voltage up to 6 kV. Past this electrode supply voltage, ion densities ceased increasing and began to decline in some locations within the premixed flame. The increased ion density is caused by an increase in ionic wind force and cathode sheath thickness. The plateau in density is due to the cathode sheath fully encompassing the flame front which is the ion source, thereby collecting all ions in the flame. The spatial density data support the ionic wind hypothesis and provide further explanation of its limits based on the plasma sheath.

A premixed methane-air flame was produced on a flat flame burner and exposed to electric fields between the burner and a flat grid electrode. Equivalence ratios of 0.8 and 1.0 were tested at electrode supply voltages up to 10 kV. A Langmuir probe was used to record ion current within the flame. The current increased at low potentials but decreased at higher potentials. Maximum ion current was greater for an equivalence ratio of 1.0. The change in ion concentrations was attributed to the ionic wind at low potentials and dissociative recombination at high potentials. NomenclatureI = Current lp = Langmuir probe length ni = Number density of ions q = Elementary charge r = Distance from edge of the burner rp = Langmuir probe radius SLM = Standard Liters per Minute U = Flow velocity Vb = Langmuir probe bias Vss = Electrode supply voltage y = Distance above burner grid ϵ0 = Permittivity of freespace µi = Ion mobility ϕ = Equivalence ratio

A premixed methane-air flame at the stoichiometric equivalence ratio was produced on a flat flame burner. A flat grid electrode placed above the burner was used to produce electric fields using potentials up to 27.3 kV/m. Both a single and double core Langmuir probe were inserted into the flame to record a current-voltage sweep. Measurements were repeated at multiple points in the flame and at different electric field strengths. Results were used to determine the electron temperature as a function of axial location and electric field strength as a means of assessing how effective dissociative recombination is in influencing flame behavior.