Improvement of Trapped Magnetic Field of a REBCO Bulk Magnet Activated by Pulsed Field Magnetization in a High-Cooling Power Two-Stage GM-Type Refrigerator

We developed a high-cooling power bulk magnet system using a 12 K two-stage Gifford-McMahon (GM)-type refrigerator with a cooling ability of 12 W at 20 K in our previous study. When a single pulsed field was applied using a GdBCO bulk, the maximum trapped field of 3.59 T at the center of sample surface and the total magnetic flux of 2.89 mWb were achieved. In this paper, we aim to improve the trapped magnetic field by increasing the size of soft-iron yoke. When the same experiment was carried out using the same bulk, the trapped field was increased to 3.85 T. Moreover, the total magnetic flux reached a value of 3.97 mWb by a multipulsed field magnetization.