Analysis of non-Maxwellian fusion reaction rates with electron screening

The resonant T(d,n)4He and non-resonant 3He(3He,2p)4He fusion reactions are analysed. Their thermal reactivities are calculated, assuming that the distribution function of the reacting nuclei could be non-Maxwellian. This analysis can be performed by means of the Abramowitz's functions, their generalization, and asymptotic expansions at low T, which are derived here. Analytical expressions of reactivities are given and the effects of deviations from Maxwellian distribution and of the electron screening are discussed. (orig.)