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

We have measured the electron drift velocity, longitudinal diffusion, and the effective ionization coefficients in the gaseous mixture of CF3I-SF6 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% CF3I. We have found that the limiting field strength E/N-lim of the CF3I-SF6 mixture is superior to that of CF3I-N-2, and always higher than that of SF6. Moreover, over the whole mixture range, the range of the limiting field strength for the CF3I-SF6 mixture is 360-437 Td, these limits corresponding for pure SF6 and CF3I, respectively.