Performance tests of Bi-2223 pancake magnet

Bi-2223 pancake magnet was tested at various temperatures using a GM type cry ocooler in order to investigate the applicability of the Bi-2223 to the magnetic separation system. The magnet consisted of 17 double pancake coils made by a powder-in-tube method. The dimension of the magnet was 79 mm bore, 130 mm outer diameter and 130 mm height. The pancake coil at the top of the magnet which was located at a greatest distance from the cooling stage showed the lowest thermal stability of the 17 coils. Below similar to 50 K, a maximum operating current density for which the magnet was stably operated was almost equal to I-c defined with 10(-13) Omega m criterion. At 30 K, the maximum operating engineering current density was 8600 A/cm(2) which generated a field of 1.0 T at the center of the magnet. At 20 K, we repeated the excitation of the magnet up to 1.1 T at several excitation speeds. At a speed of 2 T/min, the temperature of the magnet slightly increased with increasing the number of cycles, but the temperature saturated at cycles of similar to 8. These results indicate that a Bi-2223 pancake magnet is the promising candidate for the magnetic separation system. (C) 1998 Elsevier Science Ltd. All rights reserved.