Longitudinal Critical Current Profiles in Coated Conductors Examined by Transport and Magnetization Measurements

Critical current (
I_c
) variations along the coated conductor (CC) have a significant impact on the conductor stability and quench behavior. In the direct current (DC) transport case, localized
I_c
minimum can lead to the formation of a region with a higher electric field. Joule heating in such a region can disable the operational functionality of the device. Then a sufficiently detailed knowledge of the longitudinal profile of the conductor
I_c
is in the first place necessary in assessing the conductor eligibility for a specific application. In the second place, it serves to design appropriate electro-thermal stabilization, securing an effective operation, and reducing the probability of conductor degradation during the quench. We report on the experimental investigation of longitudinal
I_c
homogeneity of
CC
observed by means of transport and magnetization measurements. Basic information is the CC data from the producer on
I_c
profiles obtained with ∼1-milimeter spatial resolution by Tapestar
^TM
XL. We compare it with the result obtained by multi-channel DC transport measurement with 3-millimeter spatial resolution between neighboring contacts on a multiprobe device. Then the whole sample is characterized by a complex AC susceptibility experiment. We analyze possible causes of observed discrepancies between respective methods and discuss the relevance of various techniques for the determination of longitudinal
I_c
profiles in commercial CC.