Spatially resolved measurements of the physical plasma parameters and the chemical modifications in a twin surface dielectric barrier discharge for gas flow purification

A twin surface dielectric barrier discharge consisting of an aluminium oxide plate with grid‐structured copper traces on both sides is presented. Due to the size of the electrode configuration spatially resolved optical emission spectroscopy for characterisation of the discharge is performed on two different length scales in order to show its homogeneous behaviour. A broadband echelle spectrometer is employed for a comparison of the plasma parameters at different sites along the copper traces with a spatial resolution on a scale of millimetres. In addition, an ICCD camera with bandpass filters yields homogeneity of the plasma parameters on a scale of micrometres at a given node of the grid‐structured copper traces. The discharge is shown to be homogeneous all along the electrode. However, due to the changing composition of the gas stream, it cannot be concluded that the gas phase chemistry follows the same trend. Therefore, FTIR spectroscopy of cysteine is used to monitor the spatial dependence of the gas phase chemistry, showing a transition from purely oxygen‐related modifications at the front of the electrode to a mixture of oxygen‐related and nitrogen‐related modifications at the rear.