Low Field Superconducting Magnet with Nb-Ti Wire

A low-field square ended superconducting magnet has been constructed with Nb-Ti alloy as a coil, which is to be used for the nuclear magnetic resonance experiment at helium temperatures. The wire is wound around a brass bobbin (the inner diameter 10 mm and the length 60 mm). To operate the magnet in a persistent mode, a persistent current switch with the same wire is attached The magnetic field strength at the exciting current 20 A is about 12kG, which is measured by a Bi-sensor. No decay of the persistent current is observed with time. The field strength vs. the current and the field distribution in the magnet are measured, which are in good agreement with the calculated values