Search

Fujikura has developed production techniques of REBa2Cu3Oy (REBCO, RE = rare earth) coated conductors (CCs) and provided high-performance REBCO CCs with longlength and high homogeneity of the critical current. REBCO CCs have a low c-axis strength (delamination strength) which originates from the layered structure. When an epoxy-impregnated REBCO coil is cooled, the radial thermal stress is generated. The stress could cause the delamination of REBCO CCs and lead to degradation of the coil. Therefore, it is important to evaluate the exact delamination strength of the CCs. In this paper, we evaluated the failure probability of the epoxy-impregnated coils at 77 K.We introduced Weibull analysis considering the stress distribution and the sample size effect, and estimated the actual delamination strength of the REBCO CCs. By using the evaluation method, we confirmed the strength enhancement by process improvement. [ABSTRACT FROM AUTHOR]

Fujikura Ltd., Chiba, Japan, has developed stable and high-throughput production techniques for REBCO coated conductors (CC) by using large-area ion-beam-assisted-deposition (IBAD), and hot-wall type pulsed-laser-deposition (PLD). Recently, we have been attempting to dope BaMO3 (BMO, M: Zr or Hf) to REBCO layer in order to enhance in-field critical current density (Jc ). In the course of optimizing deposition conditions of PLD for BaHfO3 doped EuBCO films on IBAD templates, "high Jc condition" and "high growth rate condition" were found. For samples prepared under these conditions, the magnetic field angle dependence of Ic and REBCO thickness dependence were investigated. Finally, we succeeded in fabricating a 300-m-long CC with uniform Ic distribution at the high-growth-rate condition. The longitudinal Ic homogeneity (defined as standard deviation divided by average) at 77 K evaluated by magnetization method was 2.6%, which is comparable to nondoped conductors. Transport in-field Ic for the both end points were 1756 and 1786 A/cm at 30 K, 2 T, respectively. [ABSTRACT FROM AUTHOR]