Progress in Processing of Thin Wall HTc Bulk Superconducting Cryomagnets

Abstract

We report on our progress in the preparation of single domain of high temperature superconducting (HTS) bulk YBCO and GdBCO cryomagnets with multiple holes. Three mains steps have been explored and discussed in this study: (i) Gd2BaCuO5 (Gd211) and Y2BaCuO5 (Y211) and thin wall preforms shaping by the extrusion technique. (ii) GdBa2Cu3O3 (Gd123) YBa2Cu3O3 (Y123) single domain obtained from Y211 using the Seed Infiltration Growth (SIG) process. (iii) Annealing under high oxygenation pressure in order to improve the superconducting properties. The thin wall samples with larger specific areas offer some advantages as better thermal exchange, shorter oxygen diffusion paths, possibility to reinforce the material to overcome the mechanically stresses during magnetization. The process and the microstructural features at various stages of processing, with particular emphasis on the characteristics of Gd211 and Y211 inclusions are discussed. Properties like the magnetic trapped field at different temperatures, the superconducting transition temperatures, and critical current densities of the resulting composites are presented and compared with their values in samples processed by other variants of the melt textured growth process.