Effect of Crossover Turns in Double-Pancake Winding on Magnetic Field Homogeneity of HTS NMR Magnet

• Published in: IEEE transactions on applied superconductivity Vol. 29; no. 5; pp. 1 - 5
• Main Authors: Baek, Geonwoo, Lee, Jiho, Lee, Woo Seung, Yoon, Yong Soo, Ko, Tae Kuk
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-08-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Biot-Savart law; Coils (windings); crossover turn; Crossovers; double-pancake (dp) coil; Electrical equipment; field homogeneity; harmonic analysis; High temperature; High-temperature superconductors; Homogeneity; Magnetic analysis; Magnetic fields; Magnets; NMR; Nuclear magnetic resonance; Pareto optimum; REBCO insert; Spectrometers; Superconducting magnets; Superconducting tapes; Superconductivity; Winding; Windings
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2019.2900331

Field homogeneity of a superconducting magnet is a critical factor for nuclear magnetic resonance (NMR) spectrometers. For REBCO high-temperature superconducting (HTS) coil fabrication, layer-wound is considered a better option than double-pancake (DP) winding, in terms of field homogeneity. Nonetheless, DP winding is preferred to layer-wound owing to the ease of manufacturing and the difficulty in making long REBCO tapes. However, DP winding has an inevitable crossover turn between the top and bottom layers. For magnets with an HTS insert used in NMR spectrometers, the crossover turn could be critical for the field homogeneity. In this paper, the magnetic field generated by the crossover turn is derived based on the Biot-Savart law, and the effect of crossover turns in stacked DPs on the field homogeneity of an NMR-class HTS magnet is analyzed.