Multiple parameter optimization and spectroscopic characterization of a dielectric barrier discharge in N2

For surface treatments with plasma under atmospheric pressure, it is important to obtain a homogeneous discharge, ideally a glow discharge. Normally, a discharge under atmospheric pressure is filamentary. The aim of this work is to examine the influence of various parameters on the plasma properties and therefore on its homogeneity. For this purpose, the plasma was characterized by optical emission spectroscopy and electrical measurements. It was found that a smaller gap leads to more electronic excited species and to an increased plasma power. Furthermore, the reduction of the gap distance results in a lower rotational temperature and, above all, to an improved homogeneity of the plasma. The changes in the plasma properties with variation of the external parameters, such as gas flow or applied voltage, are much slighter with a smaller gap. Therefore, a plasma with a smaller gas gap can be run over a wider region without significant changes in its properties.