Termination Methods for REBCO Tape High-Current Cable Conductors

Three types of joint termination methods for a 2G HTS cable have been developed: YBCO-BSCCO, YBCO-YBCO, and Folding-fan soldered terminations. For the YBCO-BSCCO terminator, each YBCO tape of a cable is connected to a BSCCO tape while the other ends of BSCCO tapes are bundled together and soldered inside a copper tube. The same termination was tested more than 30 times in liquid nitrogen and helium without any problems. It was operated at 10 kA in liquid helium and more than 2 kA in liquid nitrogen. The YBCO-BSCCO termination has been confirmed to be very easy to fabricate and convenient for a cable test since it is reusable. A YBCO tape termination method without BSCCO tape also has been proposed. Both terminations will be very useful for 2G HTS cables. These terminations are demountable if they are not soldered at the junction between tapes. Joint resistance is greatly reduced with increasing applied pressure especially for YBCO-YBCO contact joints. However, in the case of a YBCO-BSCCO joint, the BSCCO tapes may degrade at high pressure. The contact pressure should be optimized to obtain low joint resistance. If the contact surfaces of YBCO-BSCCO and YBCO-YBCO terminations are soldered for a permanent joint, the termination resistances are lower, and better uniformity will be achieved. Another termination is the Folding-fan termination. It is a soldered joint. Joint resistance distributions among cable tapes for these termination methods have been evaluated. Mechanical contact joint resistance distributions between YBCO-BSCCO tapes and YBCO-YBCO tapes have been measured under various contact pressures and contact surface conditions at 77 K. By optimization of the applied contact pressure and contact surface treatment techniques the contact joint resistance of a termination joint can be reduced and a better uniformity can be obtained. We also discussed effects on a cable performance due to no-uniformity of termination resistances, a loop resistance between two tapes in a termination of a cable, and a series operation of two 2G YBCO Twisted Stacked-Tape Cable (TSTC) conductors.已开发出三种适用于第二代高温超导（2G HTS）电缆的终端接头方法：钇钡铜氧-铋系高温超导（YBCO-BSCCO）型、钇钡铜氧-钇钡铜氧（YBCO-YBCO）型以及折叠扇型钎焊终端。针对YBCO-BSCCO型终端，电缆的每一根钇钡铜氧（YBCO）带材均与一根铋系高温超导（BSCCO）带材相连，而所有铋系高温超导带材的另一端则汇聚束扎，并钎焊于铜管内部。该类终端已在液氮与液氦环境中完成超30次测试，未出现任何故障；其在液氦环境下可承载10千安电流，在液氮环境下可承载超过2千安电流。经证实，YBCO-BSCCO型终端极易制备，且因可重复使用，非常便于电缆测试。此外，研究人员还提出了一种无需铋系高温超导带材的钇钡铜氧带材终端方案。上述两类终端均对第二代高温超导电缆极具应用价值。若不在带材接头处进行钎焊，此类终端均可实现拆卸。随着施加压力的提升，接头电阻会显著降低，针对YBCO-YBCO接触式接头而言这一效果尤为明显。但对于YBCO-BSCCO接头而言，过高的压力可能会导致铋系高温超导带材性能劣化，因此需优化接触压力以获得较低的接头电阻。若将YBCO-BSCCO与YBCO-YBCO型终端的接触面进行钎焊以形成永久性接头，则终端电阻会更低，且均匀性更佳。第三种终端为折叠扇型终端，其属于钎焊接头。研究人员已针对上述三种终端方法下的电缆带材接头电阻分布开展了评估，并在77开尔文环境下，针对不同接触压力与接触面条件，测量了YBCO-BSCCO带材间与YBCO-YBCO带材间的机械接触式接头电阻分布。通过优化接触压力与接触面处理工艺，可降低终端接头的接触电阻并获得更优的均匀性。本文还探讨了终端电阻不均匀性、电缆终端内两根带材间的回路电阻，以及两根第二代高温超导钇钡铜氧扭转堆叠带材电缆（TSTC）导体串联运行等因素对电缆性能的影响。

搜集汇总

背景与挑战

背景概述

该数据集总结了三种用于REBCO带材高电流电缆导体的终止方法：YBCO-BSCCO、YBCO-YBCO和Folding-fan焊接终止。其中，YBCO-BSCCO终止方法易于制造、可重复使用，在液氮和液氦环境中经过多次测试表现可靠，最高电流达10 kA；所有方法通过优化接触压力和表面处理，能有效降低接头电阻并提高均匀性，适用于第二代高温超导电缆。