A novel REBCO conductor design to reduce screening-current field in REBCO magnets

Due to its very high critical fields, the second-generation high-temperature superconductor (2G HTS) has been, and is being, used in high-field magnets. However, a persistent screening current induced in the REBCO conductor under time-varying conditions distorts the magnetic field, spatially and temporally. We describe a novel REBCO conductor design composed of Narrow-Stacked (NS) wire, a bundle of 1-mm wide REBCO tapes. The design is based on a fundamental notion that the narrower the REBCO tape width, the smaller the screen-current field (SCF). In this paper, both experimental and simulation work were carried out to analyze SCF in a REBCO coil wound with an NS wire. We demonstrate that the critical current of NS wires can be consistent with the conventional REBCO tape to meet the application requirements. Meanwhile, NS wire indeed substantially results in small SCF, an important requirement in high-field magnets such as for NMR, MRI, and HEP that may rely on REBCO conductor.由于第二代高温超导体（2G HTS）具备极高的临界磁场，其已被并正被应用于高场磁体领域。然而，在时变工况下稀土钡铜氧化物（REBCO）导体中会感应出持续的屏蔽电流，进而在空间与时间维度上对磁场造成畸变。本文提出一种新型的稀土钡铜氧化物导体设计方案，该方案采用窄堆叠（NS）线材——即由多根1毫米宽的REBCO带材捆束而成。该设计的核心理论依据为：REBCO带材的宽度越窄，其屏蔽电流场（SCF）便越小。本文通过实验与仿真两种手段，对采用NS线材绕制的REBCO线圈中的屏蔽电流场展开分析。研究表明，NS线材的临界电流性能可与传统REBCO带材相匹配，能够满足实际应用的需求。与此同时，NS线材确实能够显著降低屏蔽电流场，而这正是核磁共振（NMR）、磁共振成像（MRI）以及高能物理（HEP）等依赖REBCO导体的高场磁体领域的重要性能要求。