ELECTRON-IMPACT IONIZATION OF HIGHLY-CHARGED URANIUM IONS

Cross sections for electron impact ionization from the 1s and 2s shell s of He-like, Li-like and Be-like U ions have been calculated by the r elativistic distorted wave method at incident electron energies up to five times the ionization energy. Differences between the results obta ined using the Moller and Coulomb interactions are attributed to diffe rences in the contribution from interference between direct and exchan ge ionization. Excellent agreement is obtained between the Moller resu lt and an EBIT experimental result for He-like U at an incident electr on energy of 198 keV.