Noise reduction performance of a YBCO cylinder in high-field resistive magnets

摘要

The field stability of high-field resistive magnets is generally inferior to that of superconducting magnets. The main reason for this is the low inductance of resistive magnets. High-precision measurements, such as those conducted using nuclear magnetic resonance, are very difficult by using high-field resistive magnets due to lack of field stability and ripples in the magnetic fields. However, recent progress in the area of high-temperature bulk superconductors indicates that it is possible to drastically improve these measurements. We used a YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) bulk cylinder made by the Nippon Steel Corporation. Its dimensions were 5 mm (inner diameter)/spl times/10 mm (outer diameter)/spl times/10 mm (height). A pickup coil was inserted into the center of the cylinder to measure ripples in the magnetic field. The bulk cylinder with the pickup coil was then inserted into a resistive magnet of the Tsukuba Magnet Laboratory. At a certain field, the bulk superconductor was cooled down from room temperature to the superconducting state. The signals of the pickup coil before and after transition to the superconducting state were compared.