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.

我们提出了一种快速算法，可将无致冷剂的磁铁通电到高度持久的状态。到达目标场后不到一小时即可实现低至0.021 ppm / h的衰减率。在接下来的48小时内，衰减率进一步下降至0.0004 ppm / h。此过程可应用于不同的目标场值，这使得使用单个磁体研究不同场中的各种NMR线变得可行。可以基于超导线的磁特性来理解建立高度稳定的磁场的机理，这些超磁导线是使用振动样品磁力计研究的。结果证实了超导线和接头的高质量。