Development of a persistent-mode NMR magnet with superconducting joints between high-temperature superconductors

Abstract

This paper describes the first persistent-mode medium magnetic field (400 MHz; 9.39 T) nuclear magnetic resonance (NMR) magnet which uses superconducting joints between high-temperature superconductors (HTSs). As the ultimate goal, we aim to develop a high-resolution 1.3 GHz (30.5 T) NMR magnet operated in the persistent-mode. The magnet requires superconducting joints between HTSs and those between an HTS and a low-temperature superconductor (LTS). Towards this goal, we have been developing persistent-mode HTS inner coils to be operated in a 400 MHz (9.39 T) NMR magnet and here we present the first prototype inner coil wound with a single piece (RE = rare earth)Ba2Cu3O7−x (REBCO) conductor. The coil and a REBCO persistent current switch are connected with intermediate grown superconducting joints with high critical currents in external magnetic fields. To evaluate the performance of the joints in an ultimately stable and homogeneous magnetic field, the coil is operated in the persistent-mode, generating 0.1 T, in a 9.3 T background magnetic field of a persistent-mode LTS outer coil. The magnetic field drift over two years of the 400 MHz LTS/REBCO NMR magnet is as small as ∼1 ppm, giving high-resolution NMR spectra. The magnetic field drift rate over the second year was 0.03 × 10−3 ppm h−1, which is more than three orders of magnitude smaller than that required for an NMR magnet, demonstrating that the superconducting joints function satisfactorily in a high-resolution NMR system. The corresponding joint resistance is inferred to be <10−14 Ω.

Primary Structure of Glycans by NMR Spectroscopy

“…1 H, 15 N-SOFAST-HMQC and 1 H, 15 N-BEST-TROSY NMR spectra of proteins at 1.2 GHz have been acquired and were compared with respect to resolution and sensitivity to spectra obtained at 900 and 950 MHz, which resulted in clear improvements at the highest magnetic field; these results are promising for future applications to glycans using ultra-high field NMR spectroscopy at > 1 GHz. To obtain even higher magnetic field strengths for NMR spectrometers operated in a persistent mode, it will be essential to construct high quality superconducting joints between HTS coils as well as between HTS and LTS wires in order to reach such goals. , Furthermore, the HTS can be used in another very interesting area of NMR spectroscopy, viz., in the construction of cryogen-free power-driven magnets, as was shown by an HTS magnet operating at 9.4 T corresponding to a 1 H frequency of 400 MHz . The operation temperature of the magnet is 14–18 K, which allows the magnet to maintain the superconducting state, using a high-stability power supply and a helium compressor.…”

“…To obtain even higher magnetic field strengths for NMR spectrometers operated in a persistent mode, it will be essential to construct high quality superconducting joints between HTS coils as well as between HTS and LTS wires in order to reach such goals. 470,471 Furthermore, the HTS can be used in another very interesting area of NMR spectroscopy, viz., in the construction of cryogen-free powerdriven magnets, as was shown by an HTS magnet operating at 9.4 T corresponding to a 1 H frequency of 400 MHz. 472 The operation temperature of the magnet is 14−18 K, which allows the magnet to maintain the superconducting state, using a high-stability power supply and a helium compressor.…”

Current Status of High Temperature Superconducting Materials and their Various Applications

“…12. Persistent current operation tests were carried out by connecting the 400 MHz magnet system at RIKEN and negligible small change in magnetic field was confirmed for both joints [64,65]. As mentioned above, 30.5 T superconducting magnet with persistent current circuit for 1.3 GHz‐NMR system will be fabricated in a few years.…”

Design and optimization of a fault‐tolerant demultiplexer based on nano‐scale quantum‐dots

“…Using state-of-the-art integrated circuits, limited fluctuations and excessive leakage current were minimized. 1 On the one hand, scaling down the transistor technology has created severe power consumption, physical dimensions, and leakage current problems. These flaws have prompted extensive efforts to find acceptable alternatives.…”