New technologies to solve environmental problems are in demand nowadays. Existing methods cannot always be used because they are too expensive, have unwanted byproducts or simply don’t work. A new approach is to create active species in situ so transport losses can be avoided. Pulsed corona discharges is such a method. Its principle is that high energy electrons are created during the propagation phase of the streamer. These electrons dissociate molecules and create radicals such as O, OH, N₂(A) and indirectly HO₂, O₃ and others. All these radicals start chemical reactions which cause, mainly, oxidation of impurities present in the gas or water. This makes it possible to convert NO and/or SO₂ into acids and hydrocarbons into CO₂ and H₂O.

The applicability of the method is demonstrated in many laboratories. The research now is aimed at obtaining more detailed information in order to understand, optimize and scale up the process. In our group this is done with electrical, optical and chemical measurements which are compared with results from numerical modeling. The work is performed in cooperation with several other groups and within the framework of EVE&M and TDO.

The photos show two examples of a pulsed corona in water. The appearance of the discharge path is quite similar to lightning in air. The size scales with the density of the medium, i.e. a factor 1000.