The no-insulation, or more precisely, controlled-resistance coil winding method, nowadays being exclusively used for high-Temperature superconducting solenoids, has proven its effectiveness for improving quench protection. When considering low-Temperature superconductor magnet technology, which is mostly focused on stability and training issues, controlled-resistance insulation windings are directly addressing these aspects as well. Fully soldered coil windings of non-insulated turns can also show superior mechanical properties and feature simplified manufacturing when compared to epoxy impregnated coil windings and are of high practical interest for quasi-stationary magnets provided the related charging time constant can be controlled and kept low enough. For demonstrating the principle feasibility two demonstrator coils were developed using NbTi/Cu wire with CuNi cladding of 1 mm diameter. The wire performance is reported including critical current and n-values at 4.2 K and background magnetic fields from 0 to 9 T, as well as effective transverse resistivity at room temperature and 77 K. Two solenoids with fully soldered windings comprising one layer on a 50 mm bore and three layers on a 100 mm bore, respectively, were manufactured and tested in liquid helium. Their performance is directly compared to data obtained on short wire samples. The drastically enhanced stability of the coils against thermal disturbances allows to avoid any training and enables to operate the coils up, or even slightly beyond, the short-sample critical current, resulting in generated magnetic fields of 2.2 and 3.8 T and time constants of 5 and 55 s, respectively. When initiating a quench deliberately by excessive heating or spontaneously at their limiting currents, the coils entirely switch to the normal state almost instantly, thus requiring no quench protection system. Design, manufacturing and test experiences with the two super stable coils are reported and their use and design constraints for certain applications discussed.

中文翻译：

---

使用 NbTi/Cu 线和 CuNi 包层在超薄无绝缘焊接线圈绕组中演示超过 1 kA mm-2 的工程电流密度

无绝缘，或更准确地说，受控电阻线圈绕组方法，现在专门用于高温超导螺线管，已证明其在改善失超保护方面的有效性。在考虑主要关注稳定性和训练问题的低温超导磁体技术时，可控电阻绝缘绕组也直接解决了这些问题。与环氧树脂浸渍线圈绕组相比，非绝缘匝的完全焊接线圈绕组还可以显示出优异的机械性能和简化制造的特点，并且对于准静止磁铁具有很高的实际意义，前提是相关的充电时间常数可以控制并保持足够低. 为了证明原理可行性，使用 NbTi/Cu 线和直径为 1 mm 的 CuNi 包覆层开发了两个演示线圈。报告的导线性能包括 4.2 K 时的临界电流和 n 值和 0 到 9 T 的背景磁场，以及室温和 77 K 下的有效横向电阻率。 两个具有完全焊接绕组的螺线管在 50毫米孔和 100 毫米孔上的三层分别是在液氦中制造和测试的。它们的性能直接与在短线样品上获得的数据进行比较。线圈对热扰动的显着增强稳定性可以避免任何训练，并使线圈能够在短样本临界电流以上或什至略高于短样本临界电流的情况下运行，从而产生 2.2 和 3 的磁场。8 T 和时间常数分别为 5 和 55 秒。当通过过度加热或在其限制电流下自发地启动失超时，线圈几乎立即完全切换到正常状态，因此不需要失超保护系统。报告了两个超稳定线圈的设计、制造和测试经验，并讨论了它们在某些应用中的使用和设计限制。