The close-coupling theory of electron-impact ionization of helium is studied. It is found that the “raw” convergent close-coupling equal-energy-sharing amplitudes converge to half the required amplitudes. As in the $e-\mathrm{H}$ case, solving the close-coupling equations yields amplitudes that behave as results of a finite Fourier expansion of a step function. We argue that the close-coupling formalism readily solves the $e-\mathrm{He}$ ionization problem with equal-energy outgoing electrons at all practical incident energies, and demonstrate it at the most difficult kinematic case of 2 eV above threshold.

• Received 25 July 2000

DOI:https://doi.org/10.1103/PhysRevA.63.040702