Towards species concentration measurements for a pulsed subcritical microwave-enhanced flame

Pulsed microwaves are coupled to methane/air laminar flame fronts in a stagnation flame configuration. The energy deposited in the flame front is measured using forward and reflected microwave power measurements. In order to examine the effect of this pulsed energy addition to the flame front which results in large temperature increases locally, we utilize radar REMPI to measure relative changes in the post-flame nitric oxide concentration. For microwave coupling efficiency of greater than 50 percent, the nitric oxide concentration can as much as double over the non-microwave enhanced ame. This result has important implications for the application of pulsed microwaves for lean flame enhancement and sustaining deagrations at very lean conditions. In addition, it provides insight on the mechanism by which the microwaves interact with the flame front. Progress on measuring atomic oxygen concentrations with radar REMPI in adiabatic laminar ames is also presented.