Development and testing of superfluid-cooled 900 MHz NMR magnet

✍ Scribed by Hideo Nagai; Akio Sato; Tsukasa Kiyoshi; Fumiaki Matsumoto; Hitoshi Wada; Satoshi Ito; Takashi Miki; Masatoshi Yoshikawa; Yoshio Kawate; Shigeo Fukui

• Book ID: 104112204
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 780 KB
• Volume: 41
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/s0011-2275(01)00134-5

✦ Synopsis

As the preliminary step for the 1 GHz NMR spectrometer, a 900 MHz class NMR magnet was fabricated and was successfully operated in December 1999. The magnet is made of 15% Sn±bronze-processed Nb; Ti 3 Sn, Ta-reinforced Nb; Ti 3 Sn, and NbTi conductors. All the coils are cooled with pressurized super¯uid helium. The magnet generated a ®eld of 21.20 T in a driven mode and then operated in a persistent mode at 21.17 T corresponding to a proton NMR frequency of 901.2 MHz. During the magnet excitation for 24 h, the super¯uid bath temperature was kept constant to below 1.6 K using an automatic control system. After several excitation tests, the magnet was quenched and the rupture disk of the magnet vessel was broken. The size of the cold safety valve and the structure of the rupture disk have been checked and modi®ed. Before the reassembly of the magnet cryostat, the modi®ed super¯uid cooler for cooling the magnet bath was tested.