(FR2757082-A1)      A gas purification process involves passing the gas through a dielectric tube (16) in which an electric field is created by a circulating electromagnetic wave for generating an atmospheric pressure plasma which is in local thermodynamic non-equilibrium for dissociating the gas impurities to form reactive components, these components then being eliminated by reaction with a corresponding reactive element (22, 24). The electromagnetic wave is e.g. a surface wave produced by a surfatron-guide type surface wave exciter. Also claimed is an installation for carrying out the above process.    USE -   For purifying plasma-forming noble gases such as Kr and Xe, e.g. for removal of tetrafluoromethane and methane from krypton (useful as incandescent lamp filling) and xenon after distillative separation from air, but also of other gases e.g. Ar, N2, Ne, He, O2, CO2, H2 and mixtures.    ADVANTAGE -   The process improves the efficiency of gas production lines since the electrical discharge causes irreversible transformation of the dissociated impurities to allow selective separation of impurities even when present at low concentrations.    (JP10277354-A)      A gas purification process involves passing the gas through a dielectric tube (16) in which an electric field is created by a circulating electromagnetic wave for generating an atmospheric pressure plasma which is in local thermodynamic non-equilibrium for dissociating the gas impurities to form reactive components, these components then being eliminated by reaction with a corresponding reactive element (22, 24). The electromagnetic wave is e.g. a surface wave produced by a surfatron-guide type surface wave exciter. Also claimed is an installation for carrying out the above process.    USE -   For purifying plasma-forming noble gases such as Kr and Xe, e.g. for removal of tetrafluoromethane and methane from krypton (useful as incandescent lamp filling) and xenon after distillative separation from air, but also of other gases e.g. Ar, N2, Ne, He, O2, CO2, H2 and mixtures.    ADVANTAGE -   The process improves the efficiency of gas production lines since the electrical discharge causes irreversible transformation of the dissociated impurities to allow selective separation of impurities even when present at low concentrations.    (US5993612-A)      A gas purification process involves passing the gas through a dielectric tube (16) in which an electric field is created by a circulating electromagnetic wave for generating an atmospheric pressure plasma which is in local thermodynamic non-equilibrium for dissociating the gas impurities to form reactive components, these components then being eliminated by reaction with a corresponding reactive element (22, 24). The electromagnetic wave is e.g. a surface wave produced by a surfatron-guide type surface wave exciter. Also claimed is an installation for carrying out the above process.    USE -   For purifying plasma-forming noble gases such as Kr and Xe, e.g. for removal of tetrafluoromethane and methane from krypton (useful as incandescent lamp filling) and xenon after distillative separation from air, but also of other gases e.g. Ar, N2, Ne, He, O2, CO2, H2 and mixtures.    ADVANTAGE -   The process improves the efficiency of gas production lines since the electrical discharge causes irreversible transformation of the dissociated impurities to allow selective separation of impurities even when present at low concentrations.    (US6190510-B1)      A gas purification process involves passing the gas through a dielectric tube (16) in which an electric field is created by a circulating electromagnetic wave for generating an atmospheric pressure plasma which is in local thermodynamic non-equilibrium for dissociating the gas impurities to form reactive components, these components then being eliminated by reaction with a corresponding reactive element (22, 24). The electromagnetic wave is e.g. a surface wave produced by a surfatron-guide type surface wave exciter. Also claimed is an installation for carrying out the above process.    USE -   For purifying plasma-forming noble gases such as Kr and Xe, e.g. for removal of tetrafluoromethane and methane from krypton (useful as incandescent lamp filling) and xenon after distillative separation from air, but also of other gases e.g. Ar, N2, Ne, He, O2, CO2, H2 and mixtures.    ADVANTAGE -   The process improves the efficiency of gas production lines since the electrical discharge causes irreversible transformation of the dissociated impurities to allow selective separation of impurities even when present at low concentrations.