Townsend breakdown criterion in electronegative gases

A simple mathematical formula suitable for calculating the breakdown voltage of electronegative gases under uniform and quasi-uniform fields, has been developed in this paper. The values of Townsend ionization coefficients and attachment coefficient taken from the literature [l]have been used to determine the constants of this formula. Employing the concept of the shape factor, the formula is found to be valid for practical gap configurations of quasi-uniform field distribution, such as two spheres and co-axial cylinder gaps. Breakdown voltages for different gas pressure can also be predicated.