Cryogen-free magnets are around for EPR spectroscopy for a while already, however, in recent years they also become more popular for NMR spectroscopy (solids and solutions). This article greatly demonstrate the potential of the technology.
Kryukov, Eugeny, Yury Bugoslavsky, Angel Joaquin Perez Linde, Thomas Holubar, Stephen Burgess, David Marlow, and Jeremy Good. “A Method for Fast Field Settling in Cryogen-Free Superconducting Magnets for NMR.” Solid State Nuclear Magnetic Resonance 109 (October 2020): 101684.
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. The decay rate drops further to 0.0004 ppm/h in the following 48 h. This procedure can be applied at different values of target ﬁeld, which makes it feasible to use a single magnet for study of various NMR lines at different ﬁelds. The mechanism of establishing a highly stable magnetic ﬁeld can be understood on the basis of the magnetic properties of the superconducting wire, which were studied using a vibrating sample magnetometer. The results conﬁrm the high quality of the superconducting wire and joints.