Mechanistic study of the optogalvanic effect in a hollow-cathode discharge

Simultaneous detection of the optogalvanic effect and of the laser-induced intensity variations in emission lines in a uranium hollow-cathode discharge show that a part of the absorbed laser energy is transferred to all the species in the lamp by means of electron collisions. This transfer results in a global heating of the plasma and in an increase of ion and atom densities. From the measured nonisotopic selectivity of ion production associated with the optogalvanic effect, we conclude that impedance changes in the discharge are essentially due to the heating of the plasma. It follows that the optogalvanic effect is not a suitable scheme for isotopic enrichment by cataphoresis.