Development of a superconducting magnet for nuclear magnetic resonance using bulk high-temperature superconducting materials

We developed a trapped-field magnet system using a bulk high-temperature superconducting (HTS) material (Sm-Ba-Cu-O; abbreviated as Sm123) and used it to observe a signal of H-1 nuclear magnetic resonance (NMR). The compact magnet system can fit on a table and needs no conventional refrigerant such as liquid helium. The magnet has a c-axis-oriented single-domain Sm123 bulk superconductor containing 20 wt.% Ag and was synthesized in the melt-textured process. The magnet is constructed of two cylindrical pieces, 36-mm outer and 7-mm inner diameters, respectively, and 16-mm thickness. This configuration results in magnetic field stability and suitable homogeneity for observation of NMR signal. The magnet was magnetized to 3 T by an ordinary NMR superconducting magnet by using a field cooling (FC) method. The bulk magnet was magnetized at 60K and has been kept at the temperature under 58K by using a pulse tube refrigerator. We observed 1H NMR signal from the silicon rubber with the size of 1.2 mm diameter and 1.5 mm length at 2.89 Tesla (123 MHz) and 228 kHz peak width. (c) 2007 Wiley Periodicals, Inc.