AC loss study of antiparallel connected YBCO coated conductors

Abstract

Some applications of high temperature superconducting conductors require a non-inductive winding, which may be constructed from antiparallel connected YBCO (yttrium barium copper oxide) tapes. In the case of AC applications, this antiparallel winding changes the AC losses from that of an isolated conductor. This study focuses on the effect of the spatial separation and misalignment between conductors on their AC loss behavior for YBCO conductors on both rolling assisted biaxially textured substrate (RABiTS) and ion beam assisted deposition templates in an effort to fully understand the behavior of these conductors in real world applications. For RABiTS samples, the study was carried out for all three possible configurations (the so-called back-to-back, front-to-front and same-way configurations) to clarify the effect of the ferromagnetic substrate on the AC loss behavior in these conductor configurations. Numerical simulations were also employed in some cases to compare with and elucidate experimental observations.

Development of a three-dimensional finite-element model for high-temperature superconductors based on the H-formulation

“…2-D models have proven to be in excellent agreement with measurement when the 2-D symmetry is also realized in the measurements -see for example [8,10]. In those cases, the magnetic field lines are always perpendicular to the current, and pinning and flux flow in the microscopic scale can be used to describe what happens inside the superconductor [11].…”

“…Until now, the model has been only used to simulate 2-D problems, i.e. geometries representing conductors either infinitely long or characterized by rotational symmetries (coils), and excellent agreement with experimental data has been observed, both for individual and interacting tapes [8]. However, many problems require the simulation of 3-D effects, such as coupling currents, local non-uniformities of the physical or geometrical properties, and twisted or transposed geometries.…”

AC transport current loss analysis for anti-parallel current flow in face-to-face stacks of superconducting tapes

“…The length of the arrows represents the log-scaled magnitude of the magnetic field. The normal component of the field appears only near the edges [5]. To the contrary, the magnetic field lines penetrate vertically all the region of the SC layers for the parallel current case seen in Fig.…”

“…The previous studies reveal that the ac loss was reduced for the antiparallel current flow in face to face stacks [3][4][5]. However, the ac loss increased for the SC-stack array when current flow of each SC tape in a column of the array was parallel to that of a SC tape at the next neighbor column and the same row, although the directions of the currents of the SC tapes in the column are antiparallel to each other.…”

Current Density Distribution in Multiple YBCO Coated Conductors by Coupled Integral Equations

“…In order to test our model against experiments, we measured the losses as a function of the misalignment between the two tapes carrying anti-parallel currents [4]. In the measurement we used IBAD coated conductors manufactured by SuperPower, Inc. [5], 12 mm wide, with an estimated self-field critical current of 330 A, and .…”