US laboratories are installing the first batch of 900-megahertz (21-tesla) nuclear magnetic resonance (NMR) machines months ahead of their European and Japanese competitors. With a 12% increase in resolution over their 800-MHz (18-T) predecessors, the new machines can resolve previously inaccessible protein structures. “NMR is probably the most versatile if not unique tool to study such complex structures,” says Andrey Geim, a leading expert in high magnetic fields from the University of Manchester in the UK, “and these new machines are incredibly technologically complex.” Ten 900-MHz systems are either deployed or currently in production worldwide; and the only two wide-bore models, which accommodate larger-than-usual samples, will both be in the US.
At the heart of the new machines are superconducting coils, cooled with liquid helium, that create a 21-T magnetic field uniform to one part in a billion. Any slight instability in the magnetic field can create a millikelvin temperature...
