The approach to 1 GHz plus high resolution NMR

Traditionally, increased field strength in high resolution NMR magnets has been sought for the study of the structure of molecules of increasing size. The number of spectral lines associated with larger molecules requires the increased line separation and sensitivity afforded by higher fields. Recently, additional benefits of high fields have been realized due to mechanisms of line width minimization at fields which are being approached in available spectrometer magnets. As a result, the motivation for increased field strength in NMR magnets is as strong as ever. There are currently in progress a number of programs with the objective of NMR at 1 GHz, corresponding to 23.5 T and above. The possibility of these high fields depends, as a necessary condition, on the availability of a superconductor and associated coil technology for that field. Efforts are underway for the development of HTS conductor for this application. In addition, development continues on Nb/sub 3/Sn conductor with improved high field properties. Wide bore NMR magnets are currently being fabricated to provide a field of 21.1 T, or a proton resonant frequency of 900 MHz. These magnets were conceived as platforms for the demonstration of higher fields with the incorporation of additional inner coils. Given the spatial restrictions in the present 900 MHz magnets, the prospects of achieving higher fields are examined through estimates of required current densities for given field increments.