Design of a superconducting magnetic suspension system for a liquid helium flow experiment

We discuss a preliminary design for superconducting magnetic suspension system for measurement of drag on rotationally symmetric bodies in liquid helium. Due to its diamagnetic properties, a superconducting model (for example made or coated with Nb) is inherently stable against disturbances. In addition, drag measurement may be achieved by a passive technique, where the body is allowed to deflect from its neutral position under the influence of drag. The resulting shift in flux is detected via a superconducting pickup coil. The pickup coil may be connected either to a SQUID, or a secondary loop wound around a Hall probe.