Abstract: Provided is a device for the microwave-sustained plasma treatment of gases, which comprises a hollow structure forming a waveguide intended to be connected to a microwave generator, and means for making the gas to be treated flow through the said structure in a region in which the amplitude of the electric field associated with the incident wave is high. The means for making the gas flow comprise a plasma torch for producing a plasma in the gas. The torch comprises an injector made of an electrically conducting material mounted on a first large face of the said structure and extending so as to project through an orifice made in a second large face opposite the said first large face. A gap for passage of the incident waves lies around the injector.

Abstract: The invention concerns a device for exciting a gas comprising a hollow structure (24) forming a waveguide to be connected to a microwave generator and means for circulating a gas through the structure. The gas circulating means comprise an assembly of at least two hollow tubes (46, 48) made of dielectric material respectively passing through said structure (24) in the zones wherein the amplitude of the electric field associated with the incident wave is substantially the same.

Abstract: An apparatus for the treatment of perfluorinated and/or hydrofluorocarbon gases, for the purpose of destroying them, is provided. The apparatus includes at least one high-frequency surface-wave exciter which produces surface waves, a waveguide designed to guide the surface waves produced by the at least one wave exciter to at least one hollow dielectric tube for (i) creating, when supplied with a carrier gas an atmospheric-pressure plasma and (ii) for dissociating the molecules of the perfluorinated and/or hydrofluorocarbon gases within the plasma in order to form reactive compounds, and at least one treatment unit for the reactive fluorinated compounds which is arranged on an exit side of a corresponding hollow dielectric tube.

Abstract: Device for exciting a gas comprising a hollow structure forming a waveguide, made of an electrically conductive material, connected to a microwave generator and including a passage for a hollow dielectric tube adapted for flow of the gas to be excited, the hollow structure further including a wave-concentrating region designed to concentrate microwave radiation produced by the generator onto the tube, during operation of the device, for the purpose of producing a surface wave plasma in the gas, at least one electromagnetic screening sleeve made of a conductive material, fastened to the hollow structure and extending along the extension of the passage so as to surround the hollow tube.

Abstract: Provided are a process and apparatus for purifying a gas. In accordance with the process, the gas to be purified flows through a hollow dielectric tube. An electric field is created in the gas to be purified by a traveling electromagnetic wave which travels in the dielectric tube and creates, in the gas, an atmospheric-pressure plasma which is not in local thermodynamic equilibrium, for the purpose of dissociating impurities in the gas to form reactive compounds. The formed reactive compounds are reacted with a corresponding reactive material for eliminating the reactive compounds from the gas to be purified.

Abstract: Provided is a process for purfying a gas. In the process, the gas to be purified flows through a hollow dielectric tube. An electric field in the gas to be purified is created by a traveling electromagnetic wave which travels in the dielectric tube and is suitable for creating, in the gas, an atmospheric-pressure plasma which is not in local thermodynamic equilibrium, for the purpose of dissociating impurities in the gas in order to form reactive compounds. The formed reactive compounds are reacted with a corresponding reactive material for eliminating the reactive compounds from the gas to be purified.

Abstract: A process for treating perfluorinated and/or hydrofluorocarbon gases, comprising the steps ofcreating an atmospheric-pressure gas plasma in at least one hollow dielectric tube;making the gases to be treated flow through the at least one dielectric tube in contact with the plasma for the purpose of dissociating molecules of the gases into reactive compounds; andreacting the reactive compounds with a corresponding reactive element for the purpose of destroying them.

Abstract: A method for depositing a thin film of diamond on the surface of a Fe-based substrate comprises the step of pre-treating the surface of the Fe-based substrate prior to the deposition consisting of nucleating carbon atoms on the Fe-based substrate to grow the thin film of diamond. The pre-treatment consists of supersaturating the surface of the Fe-based substrate with carbon atoms and heating it to form a diffusion barrier layer. During the pre-treatment, at least a portion of the carbon atoms are diffused into the Fe-based substrate. During the deposition process, carbon atoms are prevented by the diffusion barrier layer previously formed to diffuse into the Fe-based substrate whereby these carbon atoms remain available for the nucleation and growth of the thin film of diamond.

Abstract: Apparatus for depositing diamond on a substrate assisted by microwave plasma, comprising two zones, a plasma formation zone located in a waveguide and a diamond deposition zone located outside the waveguide. The apparatus includes means making it possible to form a stable plasma in the deposition zone, so as to considerably increase the substrate surface which can be treated.

Abstract: The present invention relates to a device for generating plasma (ionizing gas) by a propagating surface wave. The device comprises a wave launching structure mounted on a plasma vessel and connected to an impedance matching network. The latter comprises a coupler and a tuner which is either formed by a section of a transmission line or is of the lumped circuitry type. The launching structure may either generate an azimuthally symmetric or a non symmetric propagating wave. This invention also relates to a method and a device for shaping plasma which comprises a plasma vessel receiving a surface wave generator and having a serviceable portion of a size and/or shape substantially different from the shape and/or size of the portion of the plasma vessel receiving the wave generator.

Abstract: The present invention relates to a device for generating plasma (ionizing gas) by a propagating surface wave. The device comprises a wave launching structure mounted on a plasma vessel and connected to an impedance matching network. The latter comprises a coupler and a tuner which is either formed by a section of a transmission line or is of the lumped circuitry type. The launching structure may either generate an azimuthally symmetric or a non symmetric propagating wave. This invention also relates to a method and a device for shaping plasma which comprises a plasma vessel receiving a surface wave generator and having a serviceable portion of a size and/or shape substantially different from the shape and/or size of the portion of the plasma vessel receiving the wave generator.

Abstract: A device which generates plasma by energizing a column of gas with a high frequency periodic electric field of a frequency of at least 100MHz. The generating means extends over only a part of the gas column and the power of the energizing field is such that the plasma generated includes and extends beyond said part of the gas column. In one embodiment the gas column is contained in an elongated insulating casing and the generating means comprises a first metallic tube open at both ends and surrounding a part of the casing, a second tube enclosing the first, and a connecting ring between the first and second tubes.