Impulsive breakdown behaviour of gases and gas-solid interfaces

Pre-breakdown and breakdown processes in gases and in gas-solid dielectric systems have been intensively studied, experimentally and theoretically, for many decades. The fast transient processes in gases stressed with high-field impulses, including ionisation fronts, plasma streamers and leaders, may lead to the formation of highly conductive post-breakdown plasma channel. Further understanding of the pre-breakdown processes and breakdown characteristics of gases and gas-solid interfaces is important for optimisation of the high voltage systems, for insulation coordination and for the development of different technological processes and applications which are based on the transient plasma discharges. However, despite significant research efforts in this field, the complex mechanisms and processes associated with the development of transient plasma structures in gases and across gas-solid interfaces are not fully understood.

In the present work the dielectric performance of different gases and gas-solid interfaces have been investigated. The field-time breakdown characteristics of common gases: air, nitrogen and carbon dioxide have been analysed using two analytical approaches, the kinetic and drift-diffusion models. The impulsive breakdown characteristics of gas-solid interfaces, formed between different dielectric materials and dry air, nitrogen and carbon dioxide have been experimentally studied, the breakdown voltage and time to breakdown were obtained for all tested gas-solid interfaces. Open shutter images of the post-breakdown plasma channels have been obtained for all tested gas-solid interfaces; these images were analysed and classified according to propagation path of the plasma channels. The dynamic resistance of the post-breakdown plasma channels formed in different gases have been analysed and modelled using different approached including the methods proposed by Braginskii and Kushner.

The results obtained in this work will help in further understanding of the pre-breakdown mechanisms and breakdown characteristics of gases and gas-solid interfaces, these results can be used in the optimisation of dielectric topologies for the use in high voltage and plasma systems, in the development of practical breakdown plasma-based applications and technologies.