THE 1S-2S AND 1S-2P EXCITATION OF HELIUM-IONS BY ELECTRON-IMPACT

The electron impact excitation of He** plus to the n equals 2 level is studied using two variants of the polarized orbital method, one due to Daskhan et al. and the other due to Temkin and Lamkin. The present results for 1s-2p total excitation cross sections are in fair agreement with the measured values. For the 1s-2s excitation, our values fail to reproduce the more elaborate theoretical prediction by Morgan near the threshold energies.