Limiting field strength and electron swarm coefficients of the CF₃I–SF₆ gas mixture

Abstract

We have measured the electron drift velocity, longitudinal diffusion, and the effective ionization coefficients in the gaseous mixture of CF 3 I–SF 6 over the density-normalized electric field intensity E / N , from 375 to 500 Td (1 Td = 10 −17 V cm 2 ). A pulsed Townsend technique was used. Overall, the gas mixture compositions were varied from 50 to 90% CF 3 I. We have found that the limiting field strength E / N lim of the CF 3 I–SF 6 mixture is superior to that of CF 3 I–N 2 , and always higher than that of SF 6 . Moreover, over the whole mixture range, the range of the limiting field strength for the CF 3 I–SF 6 mixture is 360–437 Td, these limits corresponding for pure SF 6 and CF 3 I, respectively.