Review of recent developments in ultra-high field (UHF) NMR magnets in the Asia region

Abstract

This paper reviews recent developments in ultra-high field (UHF) superconducting magnets for nuclear magnetic resonance (NMR) in the Asia region, in particular those for high-resolution NMR magnets using high-temperature superconductor (HTS) coils. In Japan, a power supply driven-mode 1.02 GHz (24.0 T) NMR magnet using a Bi-2223 inner coil was developed in 2015, providing the first high-resolution NMR at a 1H NMR frequency of >1 GHz (23.5 T). In late 2017, a new project started for developing a persistent-mode 1.3 GHz (30.5 T) NMR magnet comprising a REBCO inner coil, a Bi-2223 middle coil, and a low-temperature superconductor (LTS) outer coil. The magnet employs the newly developed state-of-the-art superconducting joints between HTSs necessary for the persistent-mode operation, as well as magnet technologies providing an ultra-high magnetic field of >30.5 T with high temporal stability and spatiality homogeneity for high-resolution NMR measurement. In China, a ~20 mm-cold bored magnet comprising an LTS outer coil and no-insulation (NI) REBCO inner coils was developed and recorded a field of 32.35 T, the highest magnetic field ever achieved with an all-superconducting magnet, which can be used as a small cold-bored NMR. In Korea, a liquid helium-free 400 MHz (9.39 T) all REBCO NMR magnets using NI winding was developed, which is operational. These technologies provide future perspective for a UHF NMR magnet with key features of persistent-mode operation, an operating field of 1.4 GHz using (32.9 T)-class magnets, and the liquid helium-free operation.

Current Status of High Temperature Superconducting Materials and their Various Applications

“…In addition, a superconducting magnet with a center magnetic field of 28.2 T, in which a coil using RE123 tapes made by Fujikura is inserted, is used in the commercial 1.2 GHz-NMR system developed by Bruker. In addition, the development of a 1.3 GHz-NMR device began in 2017 under the JST-MIRAI project in Japan, and the design of a 30.5 T superconducting magnet and the development of superconducting joints between cuprate superconducting wires have been progressing [51,52]. This superconducting magnet is a combination of Nb-Ti, Nb 3 Sn, Bi2223, and RE123 coils, and superconducting joint technology between cuprate superconducting tapes is required to enhance its function as an NMR device by persistent current operation.…”

Basics of Protection Technology for REBCO Coils ―with a Comparison to Low-Temperature Superconducting Coils―

“…希土類系高温超電導線材 (REBa2Cu3O7-δ, RE：Y, Gd 等 の希土類。以下「REBCO 線材」と略記)は、現状最も優れ た超電導特性(高温、高磁場下で、高い臨界電流を維持) と高機械強度(引張応力)を有していることから、30 T を超える超高磁場コイル [1][2][3][4] をはじめ、医療用 MRI 5,6) や医 療用加速器 [7][8][9] 、或いは、Compact 核融合用コイル 10) 、さ らに舶用や航空機用電動機への応用 11) などを目指した研 究開発が国内外で進められ、最近では 1.2 GHz (28.…”

First Validation of Robust REBCO Insert Concept on a Large 20-Pancake Prototype Reaching Up to 25 T

“…It consists in an 11 T BSCCO insert with a 14 T LTS outsert. It was the first user magnet operating above 23 T, and is still to date the only conduction-cooled magnet operating above that limit, even though several other user or commercial magnets operate now above 25 T or are expected to do so [2][3][4]. Since then research activities were conducted at HFLSM together with Toshiba to develop the technology for REBCO insert for upgrading this magnet to reach 30 T while retaining the ease of use offered by cryogen-free operation of an insulated magnet [5,6].…”