Double-Disordered HTS-Coated Conductors and Their Assemblies Aimed for Ultra-High Fields: Large Area Tapes

Double disordered (DD) HTS layers processed via high-fluence PLD with modulated pressure and barium zirconate precipitation yield very high engineering current densities, above 900 and 600 A/mm$^2$ at 18 and 31 T, respectively, measured at 4.2 K and B$\parallel$c. Tape architecture is based on 50-100-μm-thick polished stainless steel tape which prior to DD-HTS deposition was coated with YSZ template yielding a biaxial in-plane texture with FWHM = 10-11° characterized using phi-scan XRD technique. High-resolution nanostructural analysis indicated a number of nonusual features in DD YBCO layers regarding “firework”-like orientation of nanoprecipitations /nanochains. These new features result in a very high concentration of local defects which reduce the critical current (I$_c$) measured at 77 K, self-field to about 30% of the corresponding I$_c$ in non-DD YBCO, and simultaneously lead to substantial gaining of Ic at high fields. The main result is a substantial improvement of Ic and engineering current density ($J_e$) achieved at high field and liquid Helium temperature in long length, large area tapes with 4 and 12 mm width. J$_e$ above 970 A/mm 2 at 4.2 K, B = 18 T, B$\parallel$c was achieved in 12-mm-wide tape.