Principal physical problems in laser separation of weighable amounts of a rare ytterbium isotope

A review is provided of the work on laser separation of Yb isotopes, carried out at the Institute of General Physics of the Russian Academy of Sciences and at the ‘Lad’ Scientific — Production Enterprise during the last 4 — 5 years. The processes of Yb isotope separation by the AVLIS (atomic vapour laser isotope separation) method were investigated both theoretically (by computer simulation) and experimentally. The main topics considered in the review are the ionisation selectivity, the formation of laser beams and of vapour flow in the cavity, and the extraction of ions from a plasma. A facility for producing highly enriched ¹⁶⁸Yb on an industrial scale is described. The rate of production of the enriched ytterbium is now 5 — 10 mg h^–1 (over 1 g per month). Commercially viable production of the enriched ¹⁶⁸Yb isotope by the AVLIS method was achieved for the first time anywhere in the world.