Measurements of the vapour pressure of helium-3 in high magnetic fields

Abstract

Measurements of magnetic field-induced changes in hydrostatic head corrections are reported for columns of liquid N2 and Ar at their normal boiling points and for liquid He4 between 2.15 and 4.2 K, in static magnetic fields to 15 T. The results for very high purity N2 and Ar are in good agreement with calculations based on gas susceptibilities; diamagnetic coolings of − 32 ± 1.5 and − 64 ± 6 mK are observed for liquid N2 and Ar respectively, at 15 T. However, O2 contamination in amounts as small as 0.1 at % can drastically after the observed temperature changes. The measurements on He4 above 3 K are also in good agreement with calculations based on the diamagnetic gas susceptibility. Below 3 K, the results deviate from the calculation in a paramagnetic direction; just above the λ-point, paramagnetic warnings of ∼ 10 mK are observed for a field of 15 T.