Electron impact ionization and attachment, drift velocities and longitudinal diffusion in CF3I and CF3I-N2 mixtures

w This paper reports the measurement of the electron drift velocity v(e), the longitudinal diffusion coefficient N D-L and the density-normalized effective ionization coefficient (alpha-eta)/N in pure CF3I and in the CF3I-N-2 mixtures, where a and. are the electron impact ionization and attachment coefficients, respectively, and N is the gas density. The E/N range covered was 100-850 Td (1 Td = 10(-17) V cm(2)). The present results were derived from a pulsed Townsend experiment. For pure CF3I, the values of ve and (alpha-eta)/N were found to increase linearly with E/N. Moreover, the E/N value at which ionization equals attachment, commonly referred to as the limiting field strength, was found to be E/N-lim = 437 Td, which is greater than that of SF6 (360 Td), a widely used insulating gas. For the CF3I-N-2 mixture with 70% CF3I, this E/N-lim value was found to be essentially the same as that for pure SF6.