Rotational and Vibrational Temperature Distributions for a Dielectric Barrier Discharge in Air

Spatially resolved rotational and vibrational temperatures for N 2 and rotational temperatures for N + 2 , as a function of voltage, have been obtained for an asymmetric surface mode dielectric barrier discharge using emission spectroscopy. The rotational temperatures were obtained from a nonlinear least-squares fit of a two-temperature theoretical spectrum with the measured spectra of the N 2 (C 3 Π u ― B 3 Π g ) and N + 2 (B 2 Σ + u ― X 2 Σ + g ) electronic band systems. The vibrational temperatures were obtained by applying the Boltzmann plot method to the Δv = ―2 sequence of the N 2 (C 3 Π u ― B 3 Π g ) electronic band system. It was observed that the rotational temperatures for N 2 ? and N + 2 decreased in the induced flow direction and increased with increasing voltage. Values started at 390 ± 10 K and decreased to 340 ± 10 K for N 2 and started at 500 ± 15 K and decreased to 450 ± 15 K for N + 2 . The vibrational temperatures also decreased in the induced flow direction from 3250 to 2850 ± 300 K. A difference in rotational temperatures between N 2 and N + 2 was observed for all voltages studied, and these differences increased with increasing voltage. The rotational temperatures of both species fluctuated in the spanwise direction. These fluctuations damped out in the streamwise direction and were weakly correlated with the attachment points of the microdischarges on the edge of the exposed electrode.