A homogeneous dielectric barrier discharge plasma excited by a bipolar nanosecond pulse in nitrogen and air

In this paper, a nanosecond bipolar pulse voltage with 20 ns rise time is employed to generate a low gas temperature homogeneous dielectric barrier discharge plasma both in nitrogen and air at atmospheric pressure. Images of the discharge, waveforms of pulse voltage and discharge current, and the optical emission spectra emitted from the discharge are recorded successfully under severe electromagnetic interference. The effects of pulse peak voltage, pulse repetition rate and the gap distance between electrodes on gas temperature and the emission intensities of NO (A 2Σ → X 2Π), OH (A 2Σ → X 2Π) and N2 are discussed. It is found that the emission intensities of NO (A 2Σ → X 2Π), OH (A 2Σ → X 2Π) and N2 rise with increasing both pulse peak voltage and pulse repetition rate but decrease with gap distance between the electrodes when it is above 2.5 mm. The effect of concentrations of O2 on the emission intensities of NO (A 2Σ → X 2Π), OH (A 2Σ → X 2Π) and N2 is also investigated, and it is found that the emission intensities of both NO (A 2Σ → X 2Π) and OH (A 2Σ → X 2Π) reach maximum values when the O2 concentration is 0.3%.