Measurement of ionisation, positive ion mobilities and longitudinal diffusion coefficients in SF₆at high E/N

Abstract

Using a pulsed Townsend technique, the density-normalised ionisation coefficients, alpha /N, positive ion drift velocities, v+, and longitudinal diffusion coefficients, D+, have been measured in SF6 over the E/N range from 909 to 5450 Td, and gas number density N from 0.23 to 2.3*1022 m-3; E is electric field intensity. The alpha /N values were found to be generally higher than others reported previously. The ion mobilities were in fairly good agreement with those derived from theory by Brand and Jungblut (1985), who assigned them to the SF5+ species. To the authors' knowledge, no previous ND+ data have been reported.