Analytic rates for fitted ionization cross-sections

Analytic expressions are derived for the Maxwellian rates corresponding to the ionization cross-sections fitted by Lennon et al.[J. Phys. Chem. Ref. Data 17 (1988) 1285]. The agreement between the analytic rates and those fitted by Lennon et al. is excellent in most cases. Compared with the fitted rates of Lennon et al., the analytic rates have the advantage of being uniformly valid over the entire temperature range of interest to fusion. In case where auto-ionization processes are important, they also avoid unphysical discontinuities in the slope of the rate. (orig.)