Electron impact excitation of ions

In researching electron impact excitation of ions, prediction of cross-section rates is still uncertain. This paper reviews electron-ion beam experiments. Theory is reviewed, then energy levels of the electron and He-like atom, and some of the transitions important in electron impact excitation studied. Close-coupling (coupled state) theory is treated. The distorted wave and Coulomb Born Approximations are applied. Experimental techniques are then reviewed. The plasma-based rate measurements are studied. Electron-ion beam experiments are represented schematically. The optical detection system (to observe photon emissions of electron and ion--collisions) is detailed. The parameters for the best experiments are determined. Finally, simple systems (for He+) and complex systems (for heavy ions), the experiments, and theoretical attention given them, are surveyed