Hendry, P. C. and McClintock, Peter V. E. (1987) Continuous flow apparatus for preparing isotopically pure He-4. Cryogenics, 27 (3). pp. 131-138. ISSN 0011-2275
Abstract
A He-4 isotopic purification cryostat has been developed, capable of sustained operation in continuous flow. Starting from a feedstock of helium of the natural isotopic ratio, He-3/He-4 = X3 = 10^-7, it yields a purified product for which X3 < 5 X 10^-13 at a production rate of 3.3 STP m3/h. The isotopically purified He-4 is being used for a variety of applications, including quantum evaporation experiments, studies of ion motion at the He II/vacuum interface, down scattering and containment of ultra-cold neutrons, and investigations of the breakdown of superfluidity in He-4.