Theoretical Determination of Total Electron-impact Ionization Cross Sections of Dichlorodifluoromethane (R12) and Tetrafluoroethane (R134)

SF6 has been employed as insulation and arc-quenching medium in high voltage apparatus since the 1960s. However, due to the high global warming potential (GWP) of SF6 gas, the alternative to SF6 is required. R12 and R134 gases offer good dielectric properties to be good replacements of SF6 as insulation medium considering the environmental concerns. In order to further investigate the ionization processes in those gases, the electron-impact ionization cross sections are calculated by Deutsch-Märk (DM) and its modified methods. The molecular structures and the molecular orbital compositions of R12 and R134 were determined by ab initio calculation. The results give important reference for the two SF6 substitute gases.