The differences in the ionization rates for RF induced atmospheric bre
akdown between the analytic formula given by Gurevich et al. [1978] an
d recent numerical simulations Short et al., 1991; Tsang et al., [1991
] were examined and clarified. An updated analytic formula for the ion
ization rate of air, which includes corrections due to kinetic effects
of the electron function, was derived. The formula is valid for arbit
rary ratios of RF to electron-neutral collision frequency.