Characterization of a DBD plasma jet for soft ionization

A source for soft ionization of organic molecules is presented in this paper. It is based on an atmospheric pressure dielectric barrier plasma jet, whereby the plasma is ignited inside a glass capillary surrounded by two ring electrodes. The length of the plasma jet depends on the applied gas and the gas flow. Pure He, Ne and Ar are used as operating gases. To characterize the mechanisms, which are responsible for soft ionization, spatially resolved optical emission spectrometry (OES) measurements were implemented. A special focus was put beside the emission of the different element lines also on the intensity variation of the N₂ and N₂⁺ lines, which are involved in the ionization process.