Waste Gas Decomposition by Plasmas: Development and Spectroscopic Investigation of a Microwave-generated Plasma Source at Atmospheric Pressure

In view of the world climate change the cleaning and purification of waste gases has become one of the most urgent tasks for humankind nowadays. Volatile organic compounds (VOC) and perfluorinated compounds (PFC), whose green house potential is up to 23000 times as high as that of carbon dioxide, are examples of harmful gases. The latter are widely used in etching processes in growing industry sectors like the production of semiconductors. Conventionally these waste gases are treated in oil or gas combustions which are complex to handle and produce additional waste gases, since oil or gas is used as fuel. Hot thermal plasma processes offer a promising alternative for this purpose since they provide a high quantity of reactive species and do not produce additional waste gases. This work presents the development of a novel atmospheric pressure microwave plasma torch, which provides easy plasma ignition as well as stable and efficient plasma operation. Furthermore, spectroscopic investigations of the plasma are presented as well as the suitability of the plasma source for the decomposition of waste gases is shown.