title: Nonlinear Behavior of a Shim Coil in an LTS/HTS NMR Magnet With an HTS Insert Comprising Double-Pancake HTS-Tape Coils.
abstract: This paper reports results, experimental and analytical, of the nonlinear behavior of a shim coil in the presence of an HTS coil assembled with double-pancake (DP) HTS-tape coils. The experimental results are from: 1) operation of a 700 MHz LTS/HTS NMR magnet (LH700) consisting of a 600 MHz LTS NMR magnet (L600) equipped with superconducting shim coils and a 100 MHz DP-assembled HTS insert (H100) and; 2) an experiment with a room-temperature (RT) Z1 shim coil coupled to a 50 MHz DP-as-sembled HTS insert (H50). A field mapping theory with a harmonic analysis is applied to interpret both results. Based on experimental results and analyses, we conclude that the screening-current-induced field (SCF) generated by a DP-assembled HTS insert is primarily responsible for the nonlinear behavior, including strength degradation, of a shim coil.
authors.affiliation: Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 0213, USA ( syhahn@mit.edu ; minchul@mit.edu ; bascunan@mit.edu ; wyao@mit.edu ; iwasa@jokaku.mit.edu ).
authors.forename: Seung-Yong
authors.initials: SY
authors.lastname: Hahn
authors.forename: Min Cheol
authors.initials: MC
authors.lastname: Ahn
authors.forename: Juan
authors.initials: J
authors.lastname: Bascuñán
authors.forename: Weijun
authors.initials: W
authors.lastname: Yao
authors.forename: Yukikazu
authors.initials: Y
authors.lastname: Iwasa
references.citation: IEEE Trans Appl Supercond. 2009 Jul 17;19(3):2269-2272
references.pmid: 20401187
references.citation: IEEE Trans Appl Supercond. 2008 Jun;18(2):856-859
references.pmid: 31889773