August 27, 2017 to September 1, 2017
RAI Congress Center, Amsterdam, The Netherlands
Europe/Amsterdam timezone

Development of a REBCO innermost coil for a persistent 400 MHz (9.39 T) LTS/REBCO NMR magnet

Aug 29, 2017, 1:15 PM
1h 45m
Postera Area

Postera Area

Poster Presentation of 1h45m D1 - Magnets for NMR Tue-Af-Po2.05


Takeshi Ueno (Sophia University)


We are starting the development of a persistent 400 MHz (9.39 T) LTS/REBCO NMR magnet as a first step towards a 1.3 GHz (30.5 T) LTS/HTS NMR. The 400 MHz magnet consists of a layer-wound REBCO innermost coil and an LTS outer coil which are operated in individual persistent circuits. The system requires the following technical developments; (a) a REBCO-REBCO superconducting joint, located above the REBCO coil, with a current capacity of >130 A at 4 K in a field of <1 T, (b) a reasonably fast 4 K REBCO persistent current switch (PCS), operated below a heat input of <10 Wand (c) the design and fabrication of the REBCO innermost coil. We measured the transport properties of a new REBCO-REBCO superconducting joint [1], at 77 K and 4 K. The lift factor of the critical current from 77 K to 4 K and n-index at 4 K were 6.6 and 60, respectively. The assumed resistance based on the power-law V-I characteristics is much lower than the permissible resistance estimated from the required field decay rate of a NMR magnet. We developed a 4 K PCS with a resistance of 7 mΩ at 5 W and on/off times of <5 s and ~50 s, respectively. The performance of the PCS fulfills the operation requirement of the present magnet. The major challenge in the fabrication of the REBCO innermost coil is to avoid degradation of the performance of the terminal conductors connected to the PCS terminals since the REBCO conductor is easily degraded by handling and electromagnetic forces. We will present the results of persistent operations at 77 K and 4.2 K.
[1] T. Nagaishi et al., Presented at 1st Asian ICMC and CSSJ 50th Anniversary Conference, 3A-p02, Kanazawa, Nov.7-10 (2016)
This work is supported by the MEXT NMR Platform Program.

Submitters Country Japan

Primary author

Takeshi Ueno (Sophia University)


Dr Hideaki Maeda (riken) Mr Kazama Yamagishi (Sophia University) Mr Kentaro Kajita (Sophia University) Mr Kotaro Ohki (SEI) Mr Takashi Yamaguchi (SEI) Mr Tatsuoki Nagaishi (SEI) Tomoaki Takao (Sophia University) Dr Yoshinori Yanagisawa (riken) Dr renzhong piao (riken)

Presentation materials