Calculation of the minimum breakdown voltage of inert gases in static fields

Using the analytical expression for the maximum ionization coefficient of the inert gases η_max = 0.325 1/V_i (V_i is the ionization potential of the atom) a more precise expression is obtained for the minimum breakdown voltage of inert gases as a function of the γ-processes at the cathode: $$left( {Us} right)_{min } = 3.08 V_i lnleft( {frac{1}{gamma } + 1} right)$$ .