High Field Magnets With HTS Conductors

35.4 T field generated using a layer-wound superconducting coil made of (RE)Ba2Cu3O7−x (RE = rare earth) coated conductor

“…Trapping of He gas was exacerbated by the fact that the coil almost entirely filled the 39 mm inner diameter of the cryostat leaving little space for cryogen. At full field, the coil operated at 196 A, which created significant maximum hoop stress levels of about 340 MPa, which however, were well within the maximum of about 760 MPa that we previously measured on REBCO layer-wound test coils 10 . At conductor dimensions of 4.02 mm x 0.096 mm, the engineering critical current density J e was > 500 A/mm 2 .…”

“…Short length defects along REBCO coated conductors have been seen previously in microstructural and in magneto optical investigations on several samples and seem to be endemic at the present time 6 . This layer-wound coil and earlier prototype pancake-wound coils 10,11 demonstrate that REBCO coated conductors have developed into a suitable basis for a superconducting magnet technology that allows major advances in magnetic field generation at 4. This work was supported by the NSF under DMR award 0654118.…”

Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

“…We ascribe the excellent pinning performance at high temperatures to the high density (equivalent vortex matching field ∼7 T) of self-assembled BZO nanorods, while the low temperature pinning force is enhanced by large additional pinning which we ascribe to strain-induced point defects induced in the REBCO matrix by the BZO nanorods. Our results suggest even more room for further performance enhancement of commercial REBCO coated conductors and point the way to REBCO coil applications at liquid nitrogen temperatures since the critical current density J c (H//c) characteristic at 77 K are now almost identical to those of fully optimized Nb-Ti at 4 Thanks to its high critical temperature T c , high critical current density J c , high irreversibility field H irr , and moderate anisotropy parameter γ , REBa 2 Cu 3 O x (REBCO, where RE = rare earth) thin films grown on flexible and mechanically strong substrates can exceed the temperature and field application limits of the Nb-based low temperature superconductors, and enable superconducting applications in a broad temperature and magnetic field regime now exceeding 35 T at 4 K. [1][2][3] However, further J c and H irr enhancement and anisotropy reduction are strongly desirable for compelling, costeffective applications, and especially to enable multi-Tesla fields in a temperature regime of 30-77 K. [4][5][6] Enhanced vortex pinning is needed both to raise higher temperature irreversibility fields and to raise J c so that overall conductor current density J E can reach the required high values of the order of 500 A/mm 2 . Adding higher densities of nanoscale defects with strong vortex pinning properties is the most efficient strategy.…”

REBCO tape performance under high magnetic field

“…Some other orientations between these two specific cases can be also found but most of the time, the width of the tape is reduced in order to accommodate the measurement probe limitation [20,21]. At 4.2 K (liquid helium bath), more than 1000 A can pass through a 4-mm tape in parallel magnetic field [22].…”