Superconducting magnets for 200-400 MHz high-resolution NMR spectroscopy

Designs are described for the magnet of a 400 MHz spectrometer (induction 9.4 T), for which the fairly stable NbTi multifilamental superconductors (50 to 100 filaments in a Cu matrix) are still suited. The superconductor diameter in the sections is varied, e.g. from 0.5 to 0.8 mm, so that the current density should be adapted to the local field. A method of combining the multifilamental NbTi superconductors (junction resistance 10-11 to 10-14 ohm) was developed for attaining stability in time. Simultaneously with the 400 MHz magnet for a high resolution spectrometer, a 200 MHz magnet for NMR tomography, for in vivo spectrometry of small biological objects, etc., is being designed. (Z.S.). 2 figs