AC losses in Bi,Pb(2223) multifilamentary wires with square cross-section

TL;DR

This study investigates AC losses in square cross-section Bi,Pb(2223)/Ag superconducting multifilamentary wires, showing reduced losses compared to tapes in perpendicular fields and analyzing effects of twist pitch and barriers for potential applications.

Contribution

It provides experimental data on AC losses in square cross-section wires, compares them with tapes and theory, and examines the influence of twist pitch and barriers on loss reduction.

Findings

Wires show significantly reduced AC losses at 47 Hz compared to tapes in perpendicular fields.

A twist pitch of about 10 mm effectively decouples filaments, with shorter pitches offering no further benefit.

Wires are suitable for applications with rotating magnetic fields or where perpendicular magnetic components are present.

Abstract

We have fabricated prototype Bi,Pb(2223)/Ag superconduting multifilamentary wires with a square cross-section. The AC losses of these wires were measured, compared with those of tapes and also compared with the theory. Wires show largely reduced AC magnetic field losses at 47 Hz, compared to those of tapes in a perpendicular magnetic field. The effects of the twist pitch and of the use of the high resisitive barriers were also investigated. The results show that the use of a twist pitch of about 10 mm is sufficient for decoupling the filaments, and that the use of very short twist pitches does not further reduce the absolute value of the AC losses. The losses in the wires are still higher than those of tapes in a parallel magnetic field, but the results show that the square or round configurations are interesting for applications where a perpendicular component of the magnetic field cannot be avoided, or for applications in rotating magnetic fields.