Pulsed Townsend measurement of electron swarm parameters in C4F7N–CO2 and C4F7N–N2 mixtures as eco-friendly insulation gas.

Recently, C₄F₇N mixtures have attracted attention as a promising SF₆ alternative due to their low global warming potential and excellent electrical performance. In this study, we introduce a newly built experimental setup for pulsed Townsend measurements as well as the physical model for the acquisition of electron swarm parameters. The effective ionization rate coefficients, electron drift velocity, and density-normalized longitudinal diffusion coefficients in C₄F₇N and its mixtures with CO₂ and N₂ were obtained. The reduced critical electric field for pure C₄F₇N at 100 Pa is determined to be 1002 Td, while it decreases with increasing pressure because of the effect of ion kinetics during the discharge process. C₄F₇N shows good synergism with CO₂ and N₂. To have a dielectric strength equivalent to that of SF₆, the mixing ratio of C₄F₇N in its mixtures with CO₂ and N₂ should be 18% and 12%, respectively. The results provide fundamental data for modeling discharges in C₄F₇N and its mixtures. [ABSTRACT FROM AUTHOR]