Recent Developments in High-Temperature Superconducting Magnet Technology (Review)

• Published in: IEEE transactions on applied superconductivity Vol. 24; no. 3; pp. 1 - 12
• Main Authors: Maeda, Hideaki, Yanagisawa, Yoshinori
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2014; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Coils; Conductors; Degradation; Electrical engineering. Electrical power engineering; Electromagnets; Exact sciences and technology; high temperature superconducting magnet technology; High-temperature superconductors; large scale applications; Magnetic fields; Magnetic resonance imaging; Magnetomechanical effects; MRI; NMR; protection; screening current; Superconducting magnets; thermal runaway; Various equipment and components; Performance evaluation; large scale applications; Burnout; High density; MRI; protection; Learning; Degradation; high temperature superconducting magnet technology; Thermal runaway; High field; Nuclear magnetic resonance; Magnetic field; High temperature superconductor; Damaging; High strength current; Magnet; screening current; Nuclear magnetic resonance imaging; Superconducting coils; Case study; Screening; Superconducting magnet; NMR; Mechanical stress; Homogeneity; Facility; AC losses; Magnetic levitation
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2013.2287707

The use of magnets made of high temperature superconductors (HTS) such as BSCCO and REBCO easily provide higher magnetic fields and higher operating temperatures, enabling dramatic improvements in superconducting magnet technology. The LTS magnet technology is very well summarized in text books written by M. N. Wilson (Superconducting magnets, Clarendon Press Oxford, 1983) and Y. Iwasa (Case studies in superconducting magnets, 2nd edition, Springer, 2009), covering such topics as stability, protection, ac loss and so forth. To the contrary, HTS conductors were commercialized only recently and therefore the magnet technology for HTS conductors remains undeveloped, especially so in the case of REBCO conductors. The technological problems for HTS coils thus far encountered are 1) an enormous effect of a screening current-induced magnetic field, 2) degradation in the coil performance due to excessive mechanical stresses applied along the longitudinal and transverse direction, and 3) the difficulty in protecting the magnet in the case of an abrupt thermal runaway. This paper reviews recent progress in overcoming these technological problems for HTS magnets. Both BSCCO and REBCO conductors have been used for HTS magnets in areas such as high field facilities, NMR, MRI, magnetic levitation trains and so forth. The effect of the screening current is the major problem for NMR, MRI, and accelerators, as it substantially distorts spatial field homogeneity and temporal field stability; on the other hand, degradation due to excessive stresses is substantial for high field magnets. Additionally, coil protection is a common and substantive problem among high current density HTS magnets in general. World-wide activities in developing BSCCO and REBCO magnets are overviewed in this paper.