A trapped field of 17.6 T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-fit steel

TLDR

Large-grain REBCO bulk superconductors trap magnetic fields limited by critical current and tensile strength, making reinforcement essential for high-field performance. The study demonstrates a record 17.6 T trapped field in two silver-doped GdBCO bulks reinforced with shrink‑fit stainless steel. The authors used a simple, cost‑effective top‑seeded melt growth process with shrink‑fit stainless steel reinforcement to achieve the high trapped field. The resulting 17.6 T trapped field is the highest reported for bulk GdBCO, confirming the effectiveness of the reinforcement strategy.

Abstract

The ability of large-grain (RE)Ba2Cu3O7−δ ((RE)BCO; RE = rare earth) bulk superconductors to trap magnetic fields is determined by their critical current. With high trapped fields, however, bulk samples are subject to a relatively large Lorentz force, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials. In this work, we report a trapped field of 17.6 T, the largest reported to date, in a stack of two silver-doped GdBCO superconducting bulk samples, each 25 mm in diameter, fabricated by top-seeded melt growth and reinforced with shrink-fit stainless steel. This sample preparation technique has the advantage of being relatively straightforward and inexpensive to implement, and offers the prospect of easy access to portable, high magnetic fields without any requirement for a sustaining current source.