This paper presents experimental and simulation results of a screening current induced magnetic field (SCF) in a high temperature superconductor (HTS) insert that constitutes a low-/high-temperature superconductor (LTS/HTS) NMR magnet. In this experiment, the HTS insert, a stack of 50 double-pancake coils, each wound with Bi2223 tape, was operated at 77 K. A screening current was induced in the HTS insert by three magnetic field sources: 1) a self field from the HTS insert; 2) an external field from a 5-T background magnet; and 3) combinations of 1) and 2). For each field excitation, which induced an SCF, its axial field distribution and temporal variations were measured and compared with simulation results based on the critical state model. Agreement on field profile between experiment and simulation is satisfactory but more work is needed to make the simulation useful for designing shim coils that will cancel the SCF.

中文翻译：

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LTS/HTS NMR 磁体双煎饼 HTS 插入物中屏蔽电流感应磁场的空间和时间变化


本文介绍了构成低温/高温超导体 (LTS/HTS) NMR 磁体的高温超导体 (HTS) 插入物中屏蔽电流感应磁场 (SCF) 的实验和模拟结果。在本实验中，HTS 插入物是由 50 个双薄饼线圈组成的堆叠，每个线圈都用 Bi2223 胶带缠绕，在 77 K 下运行。三个磁场源在 HTS 插入物中感应出屏蔽电流：1）来自HTS 插入件； 2) 来自 5-T 背景磁体的外场； 3)1)和2)的组合。对于引起 SCF 的每次场激励，测量其轴向场分布和时间变化，并与基于临界状态模型的仿真结果进行比较。实验和仿真之间的场分布一致令人满意，但需要做更多的工作才能使仿真可用于设计可消除 SCF 的匀场线圈。