A new method to measure the temporal magnetic field instabilities in cryogen-free magnets for magnetic resonance.

Despite the obvious advantages of cryogen-free magnets for NMR such as independence of liquid helium supply and the possibility to use the same magnet at different fields, the practical application of those magnets remains limited because of temporal magnetic field distortions associated with cryogen-free cold head operation. A new experimental method for the simple and reliable detection of the temporal field distortions is described in this paper. The accuracy of the magnetic field measurements by this method is two orders of magnitude higher than by conventional MetroLab Tesla meter.

A method for fast field settling in cryogen-free superconducting magnets for NMR.

We propose a fast algorithm to energise a cryogen free magnet to a highly persistent state. A decay rate as low as 0.021 ​ppm/h can be achieved in less than an hour after reaching the target field.

On the magnetic field stability of cryogen-free magnets for magnetic resonance applications.

The temporal magnetic field variation associated with Cold Head operation in cryogen-free magnets was studied. Three different mechanisms for such variations were tested separately and rated by their importance. It was found that mechanical displacement of the magnet inside the cryostat is the main issue of magnetic field perturbation.