1. Laser atomic vapor separation

1.1 Physical principle

Uranium atoms can be ionized by the absorption of three photons in the visible range, the sum of whose energies is greater than or equal to uranium's ionization energy (6.2 eV). The three wavelengths used (which together form the photo-ionization sequence) correspond to successive resonant transitions that excite atoms from the fundamental level through two intermediate levels to a self-ionizing level (figure 1 ). The use of two-stage photoionization could be envisaged if sufficient progress were made in the field of tunable UV lasers. The spectrum of uranium's electronic transitions is very rich, with thousands of lines