Researchers from the University of Michigan at Ann Arbor have developed an efficient method of isotope separation using the magnetic fields that are produced within laser-generated plasmas. The technique provides an alternative to the toxic by-products and the expense of gaseous diffusion.

The team ablated boron nitride and gallium nitride targets in a vacuum chamber with 150- to 200-fs pulses of 780-nm light from a Ti:sapphire chirped-pulse amplified laser. They observed different times of flight for the vaporized isotopes and found that the ions were sorted by weight at the deposition site near the plume. The method produced a ¹⁰B/¹¹B ratio of 0.62, compared with its natural distribution of 0.25, and a ⁶⁹Ga/⁷¹Ga ratio of 2.8, compared with 1.5.

The group suggested that the effect is the result of the toroidal and axial magnetic fields generated within the plumes. The laser-induced plasma creates a centrifuge with the 0.6-megaGauss fields that the 2.5-TW laser produces at the surface of the target and that travel with the plume to the collection site.