This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development. During the breakdown, the discharge homogeneity is related to the ratio of the secondary emission at the cathode (γ coefficient) on the ionization in the gas bulk (α coefficient). Higher is this ratio, higher is the pressure × gas gap product (Pd) value for which a Townsend breakdown is obtained. Among the phenomena enhancing the secondary emission there is the negative charge of the dielectric on the cathode surface, the trapping of ions in the gas and the existence of excited state having a long lifetime compared to the time between two consecutive discharges. The first phenomenon is always present when the electrodes are covered by a solid dielectric, the second one is related to the formation of a positive column and the third one is specific of the gas. During the discharge development, the homogeneity is mainly controlled by the voltage or the current imposed by the electrical circuit/electrode configuration and by the gas ability to be slowly ionized. Larger is the contribution of a multiple step ionization process like Penning ionization, higher will be the working domain of the discharge. A decrease of the gas voltage during the discharge development is a solution to enhance the contribution of this process. After 20 years of research a lot of mechanisms have been understood however there is still open questions like the nature of the Inhibited homogeneous DBD, surface energy transfers, role of attachment and detachment...

Recent aircraft designs increasingly use electrical systems with higher voltages. This can lead to the occurrence of partial discharges. Testing for these phenomena is relatively poorly documented in comparison with other standardized tests available for aerospace components. After having investigated the effect of temperature, pressure, and moisture on the partial discharge inception voltage as well as the discharge characteristics, we focused on the effect of these environmental parameters on the behaviour of the energy dissipated by the discharges and on polyimide film endurance during aging under partial discharge. The results show two different behaviours for the variation of energy dissipation along aging time related to environmental conditions. In fact, when a semi-conducting layer is formed in wet conditions due to the interaction between the gaseous by-products and the water molecules, a decrease in the energy measured was revealed. In addition, the relationship between the measured dissipated energy and the polyimide lifetime was investigated and did not present constant trends for the different aging conditions. While it is clear that the material endurance was energy dependent in dry conditions, it was shown that, even when the discharge energies were higher, an increase in the endurance of the dielectric was observed when the superficial semi-conducting layer was formed.