High trapped field performances in thin-wall YBa_2Cu_3O_(7-δ) bulk cryomagnets

摘要

Thin-wall YBa_2Cu_3O_(7-δ) bulk single domains were grown from drilled preforms with a holes network in the aim of increasing the specific areas and diminishing the oxygen diffusion paths. By applying a progressive annealing at high temperature under oxygen pressure (10MPa), crack-free superconductors were obtained in a very short time (less than 3 days). A crack-free microstructure fostered large size persistent current loops, which boosted the trapped field performances. A trapped field B_(max) = 5.2T at 17 K was achieved on a 16 mm-diameter thin-wall pellet (disk surface s = 1.987 cm~2), which led to a striking trapped field density B_(max)/S = 2.617 T cm~(-2).