Measurement of the effective ionisation coefficient and the static breakdown voltage in SF₆and nitrogen mixtures

Abstract

The effective ionisation coefficient alpha /p 20 is measured for E/p 20 from 70 to 160 V cm -1 Torr -1 , and the static breakdown voltage V s between parallel plates for p 20 d from 8 to 130 Torr cm, for SF 6 and nitrogen mixtures. It is found that the alpha /p 20 of the mixtures may be approximated by a linear function of the partial pressure of SF 6 at fixed E/p 20 and that Paschen's law holds for the p 20 d may be estimated with good accuracy from the V s of the respective pure gases using an experimental formula of Takuma et al. (1972) which has been used for much larger p 20 d.