This paper presents the results of construction and operation of a persistent-mode, liquid-helium-free, small-scale prototype magnet for the development of a tabletop 1.5-T “finger” MRI system for osteoporosis screening. The prototype magnet, composed of two MgB2 coils, one superconducting joint, and a persistent-current switch (PCS) built from a portion of one coil, was wound with a one continuous ∼80-m-long unreacted and monofilament MgB2 wire, and then, reacted. The test magnet was charged successfully and generated the estimated target field of 1.75 T at 5 K with the proposed PCS operation. During initial persistent-mode, the field was slightly decayed due to the index dissipation of the joint; thereafter it sustained the persistent field of 1.7 T for 35 h. The test results validated the joint resistance of <1.2 × 10−11 as well as the proposed approach involving the PCS coil circuit model.

中文翻译：

---

桌面持续模式、无液氦 1.5-T MgB2“手指”MRI 磁体：原型磁体的构造和操作

本文介绍了持久模式、无液氦、小型原型磁体的构造和操作结果，用于开发用于骨质疏松症筛查的桌面 1.5-T“手指”MRI 系统。原型磁体由两个 MgB2 线圈、一个超导接头和一个由一个线圈的一部分构成的持续电流开关 (PCS) 组成，并用一根连续的约 80 米长的未反应单丝 MgB2 线缠绕，并且然后，反应过来了。测试磁体已成功充电，并通过建议的 PCS 操作在 5 K 下产生了 1.75 T 的估计目标磁场。在初始持续模式期间，由于接头的折射率耗散，场略有衰减；此后它维持1.7T的持续磁场35小时。测试结果验证了 <1.2 × 10−11 的联合电阻以及所提出的涉及 PCS 线圈电路模型的方法。