Charge exchange and excitation cross sections at collisions of alpha particles with be-like impurity oxygen ions in a plasma

Abstract

The charge exchange and excitation cross sections at collisions of alphas with O⁴⁺(1s ²2s ²) impurity atoms in a hot plasma for striking energies E _c varying from 20 keV to 2 MeV are determined for the first time. The cross sections are calculated using the method of close-coupling equations with 13 singlet four-electron quasi-molecular states taken as a basis. The partial cross sections of charge transfer to the 1s, 2s, and 2p states of a He⁺ ion and for O⁴⁺(1s ²2s ²) → O⁴⁺(1s ²2lnl’) (n = 2, 3) electronic excitation of an oxygen ion are found. The maximal value of the charge exchange total cross section roughly equals 2.2 × 10⁻¹⁶ cm² at E _c ≈ 0.7 MeV. The excitation total cross section has a maximum of ≈ 7.7 × 10⁻¹⁶ cm² at E _c ≈ 80 keV for single-electron excitation and ≈6.5 × 10⁻¹⁶ cm² at E _c ≈ 0.7 MeV for two-electron excitation.