MgB2 for MRI Magnets: Test Coils and Superconducting Joints Results

• Published in: IEEE transactions on applied superconductivity Vol. 22; no. 3
• Main Authors: DONG KEUN PARK, JIAYIN LING, RINDFLEISCH, Matt, VOCCIO, John, HAHN, Seungyong, BASCUNAN, Juan, TOMSIC, Michael, IWASA, Yukikazu
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01-06-2012
• Subjects: Applied sciences; Electrical engineering. Electrical power engineering; Electromagnets; Electronics; Exact sciences and technology; Materials; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Superconducting devices; Various equipment and components; MRI magnet; coil; Electrical conductivity; Splice; persistent current mode; Magnet; Doped materials; MgB; Mechanical joint; Experimental study; Superconducting wires; Nuclear magnetic resonance imaging; Multifilamentary superconductor; wire; Current carrying capacity; Critical current; Current mode; Carbon addition; Sintering; monofilament MgB; superconducting joint; Magnet coils; Reliability; Composite superconductor
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2012.2185472

Among key design and operation issues for MgB
2
relevant to MRI magnets are: uniformity of current-carrying capacity over long lengths (>2 km) of wire; and reliability of a splicing technique. This paper presents experimental results of current-carrying capacities of a small test coil and joints, both made from MgB
2
round wires, multifilament and monofilament (mono), manufactured by Hyper Tech Research, Inc. The test coils were wound with 95-m long unreacted, C (carbon)-doped MgB
2
multifilament wire, sintered at 700°C for 90 min. The critical currents were measured in the 4.2 K–15 K and 0 T–5 T ranges. We have modified our original splicing technique, proven successful with unreacted, un-doped MgB
2
multifilament wire sintered at 570°C, and applied it to splice both un-doped and C-doped mono wires sintered at 700°C. Most consistently good results were obtained using the un-doped mono wires. Also presented are results of a small joint-coil-PCS assembly of mono wire, operated in persistent mode at 50 A at >10 K.