title: Operation of a 400MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7-xhigh-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1GHz.
abstract: High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1GHz (23.5T). (RE)Ba2Cu3O7-x(REBCO, RE: rare earth) conductors have an advantage over Bi2Sr2Ca2Cu3O10-x(Bi-2223) and Bi2Sr2CaCu2O8-x(Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world's first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400MHz (9.39T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current.
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan; Graduate School of Engineering, Chiba University, Chiba 236-8522, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yanagisawa
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan; Graduate School of Engineering, Chiba University, Chiba 236-8522, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Piao
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan; Faculty of Science and Technology, Sophia University, Yotsuya 102-8554, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Iguchi
authors.affiliation: Graduate School of Engineering, Chiba University, Chiba 236-8522, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakagome
authors.affiliation: Faculty of Science and Technology, Sophia University, Yotsuya 102-8554, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Takao
authors.affiliation: Japan Superconductor Technology, Inc, Kobe, Hyogo 651-2271, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kominato
authors.affiliation: Japan Superconductor Technology, Inc, Kobe, Hyogo 651-2271, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hamada
authors.affiliation: Superconducting Wire Unit, National Institute for Materials Science, Tsukuba 305-0003, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Matsumoto
authors.affiliation: JEOL RESONANCE Inc., Akishima, Tokyo 196-8558, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Suematsu
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan.
authors.forename: X
authors.initials: X
authors.lastname: Jin
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
authors.affiliation: Center for Life Science Technologies, RIKEN, Yokohama 230-0045, Japan. Electronic address: maeda@jota.gsc.riken.jp.
authors.forename: H
authors.initials: H
authors.lastname: Maeda
keywords: REBCO high temperature superconducting coil; Screening current; Ultra-compact super-high field NMR magnet beyond 1GHz