Bifocal plasma source for treatment of gaseous pollutants

A new solution for plasma treatment of hazardous gases is presented. The main item of the concept is the concentration of microwave power, used to generate plasma and completed by a linearly extended bifocal device. Cold plasma up to 1 m in length and up to atmospheric pressure has been tested successfully with Argon at a gas flow of 0.4 m3/h and an average power of 2.8 kW. Initial experiments on pollutants in air gave a pressure limitation of the present set-up to approximately 100 mbar, due to the molecular nature of air components. It was found to be caused by the insufficient supply of pulsed microwave power limited through the experimental set-up available. Independent of that limitation it could be demonstrated that the actinism of the plasma on the pollutant is very effective. The significant destruction of halide, hazardous gases like trichlorethene and norfluorane could be demonstrated.