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An annular-mode gliding arc discharge powered by a 50Hz alternating current (ac) supply was studied in a vortex flow of dry and humid air. Its temporal evolution characteristics were investigated by electrical measurement, temporally resolved imaging, and temporally resolved optical emission spectroscopic measurements. Three discharge stages of arc-ignition, arc-gliding, and arc-extinction were clearly observed in each half-cycle of the discharge. During the arc-gliding stage, the intensity of light emission from the arc root at the cathode was remarkably higher than that at other areas. The spectral intensity of N2 (C3Πu - B3Πg) during the arc-ignition stage was much higher than that during the arc-gliding stage, which was contrary to the temporal evolutions of spectral intensities for N2+ (B2Σu+ - X2Σg+) and OH(A2Σ+ - X2Πi). Temporally resolved vibrational and rotational temperatures of N2 were also presented and decreased with increasing the water vapor content. [ABSTRACT FROM AUTHOR]

Vibrational and rotational temperatures were simultaneously determined in a kilohertz alternating current (ac) gliding arc discharge by using overlapped emission spectra of N2(C 3Πu-B 3Πg) with OH(A 2Σ+-X 2Πi) and with N+ 2(B 2Σ+ u -X 2Σ+ g ). The simulated emission spectra of OH(A 2Σ+-X 2Πi) and N+ 2(B 2Σ+ u -X 2Σ+ g ) were largely overlapped by radiation transition bands of N2(C 3Πu-B 3Πg) when the rotational temperature was elevated from 500K to 2500 K. The temporally resolved vibrational and rotational temperatures in a discharge voltage period suggested that the rotational temperature from OH(A 2Σ+-X 2Πi) was remarkably larger than that from N2(C 3Πu-B 3Πg) and N+ 2(B 2Σ+ u -X 2Σ+ g ). The ratio of number densities of excited electronic states was also determined based on the overlapped emission spectra. [ABSTRACT FROM AUTHOR]