Collision Strengths from a 29-State R-Matrix Calculation on Electron Excitation in Helium

Abstract

A previously reported 29-state R-matrix electron scattering calculation including the n ≤ 5 states of neutral helium is extended to include higher-incident electron energies and also (N + 1)-electron symmetries with orbital angular momentum L ≤ 9. Total collision strengths for many LS transitions among the lowest 19 (n ≤ 4) states are presented for the first time. All results include where necessary an estimate of the contribution to the total collision strength from those partial waves with L > 9 which are not explicitly included. Data are presented in several formats. Collision strengths for all transitions from the ground state are presented in tabular form for energies from threshold to 33.9 eV, using a mesh fine enough to resolve the main resonances in the excitation threshold impact energy region. Then, thermally averaged effective collision strengths are tabulated for all converged transitions in a range of electron temperatures from 2000 to 30,000 K. Finally, the energy-dependent collision strengths together with comparisons with a previous 19-state R-matrix calculation are plotted graphically for all transitions.