Pumping 3He in a dilute 3He- 4He solution by a magnetic field

Abstract

When a dilute solution of 3He in 4He is exposed to a magnetic field gradient and therefore contains both polarized and unpolarized particles, pumping can occur; 3He atoms are pumped from the low field region to the high field region. A 3He concentration gradient can therefore be set up in a cell which is mainly composed of a zero field volume and a 9T field volume, by the condition that the chemical potential should be uniform over the whole cell. We have detected a small concentration difference in a 0.1% solution at temperatures of the order of 10 mK, by observing the change in frequency width of a vibrating wire resonator.