Recent progress of HTS magnet using Bi-2223 Ag-sheathed wire

The authors have succeeded in developing two types of refrigerator cooled high-Tc superconducting magnets-a high magnetic field type and a large bore type. The high magnetic field type has a room temperature bore of 50 mm, an inner diameter of 80 mm and an outer diameter of 300 mm. The coil height is 200 mm, using 24 double pancakes. The magnet generated 7.1 T over 24 hours and was excited at a rate of 7 T/minute. This high ramp rate was ten times faster than that of a refrigerator cooled magnet using metallic superconducting wires. The large bore type magnet has a room temperature bore of 280 mm, an inner diameter of 400 mm and an outer diameter of 520 mm. The coil height is 18 mm using 2 double pancakes. The magnet generated 0.17 T and was excited at a rate of 0.034 T/s. These two types of HTS magnets, produced by using only Bi-2223 Ag-sheathed tapes, have been continuously operated at 20 K for practical applications.