Electron Swarm Parameters in SF6 and CF4 Gas Mixtures

Abstract

Electron swarm growth processes in SF6-CF4 gas mixtures have been studied using a pulsed Townsend method over an E/N range of 150.6–564.2Td (1Td=10-21 V·m2), where E is the electric field and N is the gas density of the mixtures. The variation patterns as a function of the density-reduced electric field of the effective ionization coefficient α, electron drift velocity Ve and longitudinal diffusion coefficient DL in SF6-CF4 gas mixtures have been determined. The dielectric strength of SF6-CF4 gas mixtures, which varies nonlinearly with the SF6 concentration in the gas mixtures, has also been determined.