Influence of Coil Size and Operating Temperature on the Transient Stability of a Multi-Stacked No-Insulation REBCO Pancake Coil System

• Published in: IEEE transactions on applied superconductivity Vol. 30; no. 4; pp. 1 - 5
• Main Authors: Onoshita, Haruka, Yoshihara, Yuka, Ueda, Hiroshi, Noguchi, So, Ishiyama, Atsushi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuits; Coil stability; Computer simulation; Conduction cooling; Current density; Current distribution; Cyclotrons; Diameters; Equivalent circuits; Finite element method; Heating systems; high-field whole-body MRI; Insulation; Magnetic fields; Magnetic resonance imaging; Magnets; Mathematical models; medical cyclotron; NMR; no-insulation coil; Nuclear magnetic resonance; Numerical analysis; Numerical models; Operating temperature; Pancake coils; REBCO coil; Temperature distribution; Thermal analysis; Thermal stability; Transient stability; Two dimensional analysis; Two dimensional models
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2020.2974847

The no-insulation (NI) coil is a technology expected to realize both high current density and high thermal stability which are essentially trade-off relationship in REBCO coil application. This technique has been studied mainly for application to small-diameter inner coils of NMR magnets exceeding 30 T. In this case, the coil is cooled using 4.2-K liquid He. We are developing an NI-REBCO coil system for high-magnetic-field whole-body MRI, and for a medical cyclotron to be used for cancer therapy. The NI-REBCO coil which we aim for development has a diameter of ∼1 m, a generated magnetic field is ∼10 T, and a conduction cooling around 30 K is assumed. Because the size, operating temperature, and magnetic field differ from those of NMR coil, it is possible that the electromagnetic, thermal, and mechanical behaviors will be quite different. In this paper, we report on these behaviors when a local deterioration occurs in NI-REBCO double-pancake coils using numerical analysis considering coil size, operating temperature, and magnetic field as parameters. For the numerical simulation, we conducted a coupled analysis of current distribution analysis based on PEEC (Partial Element Equivalent Circuit) model and thermal analysis by the 2-dimensional finite element method.