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Spectrum of dielectric barrier discharge in atmosphere

Dielectric barrier discharge (DBD) has numerous industry applications such as ozone generation, pollution control and sterilization of biological samples. The study of process of excitation and ionization is of great use for industry applications. In this paper, the spectrum of DBD in atmosphere is measured by using the special setup with two water electrodes. Nitrogen molecule spectrum (C3Πu(υ'=0) → B3Πg(υ"=0~4)) is found at range of 300~800nm. Oxygen molecule spectrum (b1∑+g → X3∑-g) is not found at the range. The excitated energy of nitrogen molecule (C3Πu(υ'=0)) is bigger than that of oxygen molecule (b1∑+g). It should be that oxygen molecule spectrum is stronger than nitrogen molecule spectrum. In fact, nitrogen molecule spectrum is very strong, but oxygen molecule spectrum is not found. In order to interpret this contradiction, process of DC discharge in atmosphere has been simulated by the Monte-Carlo computer simulation method. During the period of discharge occurring (the time is very short, about several microseconds), AC DBD can be approximately treated as DC discharge. Elastic collision and inelastic collision considered in air by electron impact, the number of electrons for excitation with E/N is analyzed emphatically. Results show that process of excitated collision of N2 with electron is far stronger than that of O2 when E/N varies from 100Td to 1000Td. The probability of the former is about 30 times bigger than that of the latter. So it is explained the above-mentioned phenomenon. The theoretical simulation is in good agreement with the experiment. The results obtained in this work are of great importance to the research of discharges at atmospheric pressure and its applications. The results provide a reference for the controlling of DBD and are of great importance to the industrial applications.