Title: Residual resistance ratio of Cu stabilizer in commercial REBCO tapes Show Chinese title

Title: 铜稳定剂在商业 REBCO 带材中的残余电阻比

Abstract: Residual resistance ratio (RRR) of Cu stabilizer in REBCO coated conductor is an important design parameter for REBCO magnets. In this work, we measured RRR of electroplated Cu stabilizer in commercial REBCO tapes. Over 130 samples were measured for the quality assurance programs of REBCO magnet projects at the National High Magnetic Field Laboratory, USA (NHMFL). The average RRR value was above 50. In order to investigate the factors that influence RRR, several samples were analyzed by using scanning electron microscopy, secondary ion mass spectroscopy, and inductively coupled plasma mass spectroscopy. We found that, in our samples, RRR was strongly correlated with the grain size. We demonstrated that RRR was primarily determined by grain boundary resistivity. Lower RRR was also strongly correlated with higher concentration of chlorine impurity. This is explained by that higher chlorine impurity hindered the grain growth in the room temperature self annealing process resulting smaller grain. Smaller grain resulted in lower RRR. In addition, thermal annealing significantly enhanced RRR. An activation energy of 0.4 eV was obtained from the annealing experiment which corresponds to the activation of Cu grain growth. Show Chinese abstract

Abstract: 残余电阻比（RRR）是REBCO涂层导体中铜稳定层的一个重要设计参数。 在本工作中，我们测量了商用REBCO带材中电镀铜稳定层的RRR。 在美国国家高磁场实验室（NHMFL）的REBCO磁体项目质量保证计划中，测量了超过130个样品。 平均RRR值高于50。 为了研究影响RRR的因素，使用扫描电子显微镜、二次离子质谱和电感耦合等离子体质谱对几个样品进行了分析。 我们发现，在我们的样品中，RRR与晶粒尺寸有很强的相关性。 我们证明了RRR主要由晶界电阻率决定。 较低的RRR也与氯杂质浓度较高有很强的相关性。 这是由于较高的氯杂质在室温自退火过程中阻碍了晶粒生长，导致晶粒更小。 较小的晶粒导致较低的RRR。 此外，热退火显著提高了RRR。 从退火实验中获得的激活能为0.4 eV，这对应于铜晶粒生长的激活。