ab-plane tilt angles in REBCO conductors

TL;DR

This paper investigates the slight tilt of the ab-plane in REBCO tapes using XRD and TEM, which affects the critical current measurements and the design of superconducting magnets.

Contribution

It provides precise measurements of ab-plane tilt angles in REBCO tapes and analyzes their origin, improving the understanding of anisotropic critical current behavior.

Findings

Measured ab-plane tilt angles using XRD at room temperature.

Analyzed the origin of tilt with TEM.

Discussed measurement uncertainty.

Abstract

Critical current (Ic) of REBCO tapes is strongly aniso-tropic with respect to the orientation of the magnetic field. Usually, Ic is at maximum when the ab-plane of the REBCO crystal is parallel to the magnetic field. In commercial REBCO tapes, it is commonly assumed that the ab-plane is coincide with the tape plane. While in fact, the ab-plane is near but slightly tilted from the tape plane in the transverse direction. To accurately measure Ic as a function of the field angle {\theta} , which is defined as the angle between ab-plane and the magnetic field direction, and to design and fabricate REBCO mag-net coils based on the measured Ic(angle), it is important to measure the tilt angle. In this work, we used x-ray diffraction (XRD) to measure the tilt angles at room temperature for a large number of REBCO conductors made by SuperPower Inc. Transmission electron mi-croscopy (TEM) was also used to investigate the origin of this tilt. The measured data are presented, and the measurement uncer-tainty is discussed.