Nuclear magnetism and flow in normal and superfluid 3He at low pressures in confined geometries

In order to study the interactions of the order parameter of superfluid 3He-B, as well as the nuclear magnetic and flow properties of normal liquid 3He, measurements were performed on liquid 3He in confined geometries. Nuclear magnetic resonance (NMR), both pulsed and continuous-wave (CW), was used in all the experiments while, in addition, a sensitive differential pressure gauge was used in the final experiment. Flow was created by use of an isochoric double-bellows flow pump. Two different experiments were performed in the B phase of superfluid 3He. In the first, liquid was confined inside two stacks of plates of separation 135 μm. With their surface normals oriented perpendicularly and using a rotatable magnetic field, a number of relative configurations of field, flow, and surface were possible. In the final experiment liquid 3He was confined in the 20 to 60 A pores of vycor glass. The enhanced susceptibility reported by others in various porous media was measured at 1.10, 3.93, and 5.45 bars for 1 mK ≤ 200 mK. At the lowest temperatures, the Curie-Weiss temperature of each pressure was approximately 0.5 mK. The behavior of flowing 3He inside the vycor was found to be quite unusual exhibiting an apparent viscoelasticity