Properties of the dielectric barrier discharge in mixtures of methane with helium

The influence of the chemical composition of the feeding gas mixtures CH₄-He on the physical properties of dielectric barrier discharge was investigated experimentally as well as theoretically. Certain changes in the shape of charge-voltage characteristics (Lissajous figures) were observed when the content of He was varied within the range 0–90%. An increase of the He concentration was found to cause monotonous but not linear decrease of the ignition voltage as well as of the burning voltage of the discharge. Measurements of the burning voltage were used to estimate the characteristic energy of electrons in the mixtures under consideration. These estimates were compared with experimentally determined values of the energy consumption for the synthesis of C₂H₂, C₂H₄ and C₂H₆, respectively. It was demonstrated that the observed dependencies of the energy consumption upon He content can be explained taking into consideration the influence of the chemical composition of feeding gas mixture upon the characteristic energy of electrons in the dielectric barrier discharge. Dedicated to Prof. Jan Janča on the occasion of his 60th birthday. The work was supported by the Sonderforschungsbereich 198 “Kinetik partiell ionisierter Plasmen”.