Abstract

In this paper results of experimental research of UF₆ dissociation using repetitively pulsed CF₄ laser are presented. The pulse energy was in the range 45-130 mJ and the pressure of UF₆ was 0.3-0.6 torr, the cell volume was 16 cm³. From pulse to pulse behavior of UF₆ photodissociation relative yield, i.e. fraction of the dissociated molecules for every pulse related to the molecules number before pulse, is investigated. It is revealed that in the irradiated region of the cell where the radiation fluence is more than the threshold one, i.e., Φ ≥ Φ₀ = 1 J·cm⁻², from 35 to 50% of the UF₆ molecules dissociate due to the first pulse and after some following pulses the relative yield sharply decreases. For a moment when the dissociated molecules fraction is a half of their quantity, the relative yield decreases by factors of 4 to 10, depending on initial UF₆ pressure in the cell and on the pulse energy. To bring out causes of such effects, we consider here processes upon the photodissociation, i.e., diffusion of its products out off irradiated region, formation of UF₅ polymers, recombination of UF₅ and UF₅ polymers with atomic fluorine, accumulation and losses of the atomic fluorine, ets. Estimations of the appropriate reaction roles and their possible effect upon relative photodissociation yield decreasing from pulse to pulse that was found in our experiments are presented.

© 1996 IEEE