Investigation of Penning ionization in atmospheric helium dielectric barrier discharges with air impurity

The change law of Penning ionization in atmospheric helium dielectric barrier discharges (DBDs) with air impurity was investigated. Discharge inception voltage and emission spectra were measured under different background air pressures (BAPs) changing from 0.8Pa to 1000Pa. Results of these two kinds of methods showed that in a range of BAP from 0.8Pa to 190Pa, discharge inception voltage decreased obviously and the 391.4 nm line intensity increased with the BAP. When BAP arrives at more than 190Pa, discharge inception voltage increased linearly obviously and 391.4 nm line intensity gradually dropped to lower value with the BAP, even a zero value at last. Emission spectra of helium decreased with the BAP. Physical processes analysis indicated that the results from both discharge inception voltage and emission spectra illustrated that Penning ionization due to helium metastables and N2 changed with the BAP, and the changes of all emission spectra intensities of helium are due to the quenching caused by N2.