Negative ion formation and motion in a mixture of CCl4 and Ar.

This paper deals with the measurement of the mobility of negative ions in the mixtures of CCl4 with Ar with the CCl4 ratio up to 33.3%. The pulsed Townsend technique was employed to produce an integrated ionic avalanche over a range of the density-reduced electric field E/N for which ionization is either negligible or absent, and attachment processes are dominant, leading to the formation of mostly CCl-4. The E/N range of measurement was 1-50 Td (1 Td=10(-17) V cm(2)). Our measurements strongly suggest that attachment is the dominant process and only negative ions are formed.