In spite of the fact that the practical applications of REBCO wires are in magnetic field and at a lower temperature than that of liquid nitrogen, optimization of processing conditions is often carried out using critical current (I_c) under a self‐magnetic field in liquid‐nitrogen as an objective function. This problem is caused by the time-consuming measurement of I_c at lower temperature and in-field conditions. The magnetic field dependent I_c is characterized by the four‐terminal method using a short sample and are approximately described as a lift factor. It has not been sufficiently examined the reproducibility of the lift factor, and whether the I_c can be optimized in the practical environment of the wire by the optimum preparation condition obtained from I_c at 77 K and self-field. In this study, I_c in a long REBCO wire was continuously measured in a 77 K, low magnetic field and at 4.2 K in an external magnetic field up to 1 T, and the relation between the two conditions has been examined by the actual measurement data, i.e., the position dependence of the lift factor. Two different samples were adopted in this study, one is a commercial wire and the other is a combinatorial sample produced by systematically changing the process‐conditions in the longitudinal direction. Both wires were fabricated by the IBAD-PLD method. Generally, the combinatorial sample refers to a sample synthesized by changing the combination of composition, but here, this concept is extended to be used for combinations of process conditions such as substrate temperature and laser output while the composition of the superconducting layer being constant. It has been found that the normalized spatial variation of I_c of the commercial long REBCO wires is almost overlapped, and there is almost no dependency on temperature and magnetic field. These results show that the lift factor of this wire is position independent because the fabrication condition is stable. On the other hand, in combinatorial sample where the process conditions are changed in the longitudinal direction of the wire, the dependency on the position, i.e., on the process condition is different between I_c of 77 K and that of 4.2 K, and therefore, the lift factor also varies depending on which condition is adopted. In addition, the process-dependence is greater in I_c of 4.2 K. This result suggests that these factors affect the lot-by-lot variation of lift factors.

This work was supported by JSPS KAKENHI Grant Number JP19H05617.