Development of a small-size superconducting bulk magnet system especially designed for a pulsed-field magnetization

Abstract: We developed a small superconducting bulk magnet system that was especially designed for a pulsed-field magnetization. The industrial applications of bulk magnets demand the miniaturization of the magnet apparatus as well as the enhancement of the magnetic field. A Gifford-McMahon cycle helium refrigerator with the ultimate temperature of 13K at the 2nd stage was adopted, and a GdBa2Cu3O7− x bulk material of 60mm diameter and 20mm thickness reinforced by a stainless steel ring was located on a cold stage. The total length of the magnetic pole was 570mm including the refrigerator, therefore, the system could easily be managed. A cooling test and a magnetizing test were carried out using a Hall sensor and thermocouples adhered on the top surface of the material. In the cooling test, the value of 22.5K at the cold stage was achieved in 3h. In the magnetizing test, five successive pulsed-fields of the same strength were applied while changing the applied field, and the time responses of the trapped flux density and temperature were measured at each stage. When a magnetic field of 6.97T was applied, the trapped field reached 2.04T, which is the highest ever reported for a pulsed-field magnetization of ϕ60mm class bulk material. [Copyright &y& Elsevier]