[Study on the characteristics of dielectric barrier discharge at atmospheric pressure by spectroscopic method].

In the present paper, stable discharges were respectively obtained in air and helium at atmospheric pressure with a dielectric barrier discharge device consisting of water electrodes. By comparing the discharges in the two gases, it was found that the discharge in air at atmospheric pressure is not uniform and micro-discharges can be discerned which are distributed on the electrode stochastically, while the discharge in helium at atmospheric pressure is quite uniform and no discharge filament can be discerned. Comparing the two kinds of discharges, the plasma generated in helium discharge at atmospheric pressure has better prospect for application in industry because of its uniformity. The discharge current waveforms in air and helium at atmospheric pressure were compared, and the results show that the discharge current pulses in air are stochastically distributed in time, while the current pulses in helium discharge appear periodically. The discharge duration in helium is much longer than that in air at atmospheric pressure. The discharge pulse length is about tens of nanoseconds in air and is about one microsecond in helium. Meanwhile the spectra emitted from the two kinds of discharges were studied, and the results show that the spectral line of 391.4 nm emitted from N2+ (B2Sigmau+ --> X2Sigmag+) is quite strong in helium discharge. On the contrary, the strength of 391.4 nm spectral line is very weak in air discharge. These experimental results are significant for the realization of uniform discharge at atmospheric pressure and industrial application of dielectric barrier discharge.