The excitation of He⁺by electrons

The excitation cross sections for the 1s-2s and 1s-2p transitions in He + induced by impacting electrons with incident energies between 44.2 eV and 217.6 eV are evaluated. The basic method used is the close-coupling approximation where the 1s, 2s and 2p states of He + are retained in an appropriately symmetrized expansion of the total wave function. Preliminary investigations of the convergence of the eigenfunction expansion indicate that the results here are much more accurate than in hydrogen. The accuracy of previous calculations is also investigated.