Recent development and mass production of high J _e 2G-HTS tapes by using thin hastelloy substrate at Shanghai Superconductor Technology

Abstract

Over the past few years, emerging applications such as high current conductors for magnets in compact fusion systems and ultra-high field insert magnets require higher engineering current density (J e ) of the second generation high temperature superconductor (2G-HTS) tapes. In this paper, the state-of-art of 2G-HTS tapes with 30 µm Hastelloy substrate at Shanghai Superconductor Technology (SST) are presented. RE 1 Ba 2 Cu 3 O 7 (REBCO, RE = rare earth) films with strong artificial pinning centers (APCs) are deposited on 30 µm thick Hastelloy substrate. Compared to those with 50 µm thick substrate, higher average critical current (I c ), better I c homogeneity and better I c linearity with film thickness increase are also achieved at 77 K self-field for tapes with 30 µm substrate, where piece lengths are up to 1 km. For a 4 mm wide tape with a total thickness of 35 µm, I c and non-copper J e values reach 600 A and 450 kA cm −2 at 4.2 K, 10 T (B//c), respectively. Transmission electron microscopy observation reveals formation of mixed landscape defects mainly including high density of splayed nanoroads and stacking faults in the REBCO film thickness direction, which is attributed to the extremely high REBCO growth rate of over 50 nm s −1 . The pinning force density (F p ) at 4.2 K, 12 T (B//c) reaches over 800 GN m −3 , and the lift factors (defined as the ratio of I c at 4.2 K, 10 T to I c at 77 K, self-field) of tapes with large I c range (100 to 500 A cm −1 -w at 77 K, self-field) also show good consistency. The annual production of 10 mm wide tapes with such pinning centers can exceed 200 km for a single set of facility at SST. No significant I c reduction is observed at bending diameter of 3 mm and the proof strength (R p0.2_0 ) is 812 MPa, both measured at liquid nitrogen temperature.

Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion

“…Indeed, our present J c (B) results are superior to many excellent results achieved with nano-columnar APC reported by other groups 7,26,[30][31][32][33][34] . We conclude, therefore, that nano-columnar defects are not indispensable for high critical current in magnetic field.…”

“…The samples differed in substrate thickness: 40, 60 and 100 µm and YBCO layer thickness: 2.55, 2.82 and 3.28 µm, respectively. In all three samples very high values of critical current were achieved, among the best reported to date for commercial 2G HTS wire 7,26,[30][31][32][33][34] . In particular, an I c at 20 K, 20 T in the 220-270 A/4 mm range and an I c at 4.2 K, 20 T in the 450-570 A/4 mm range were measured.…”

Advances in second-generation high-temperature superconducting tapes and their applications in high-field magnets

“…Bruker in Germany uses the alternate beam-assisted deposition (ABAD)-PLD route to prepare 2G-HTS tapes. It is committed to improving the current-carrying capacity of tapes at low temperatures and high fields [72] . At present, the I c per unit width of 2G-HTS tapes prepared by most companies exceeds 300 A/cm at 77 K and self-field (s.f.)…”

Superconducting properties of commercial REBCO-coated conductors with artificial pinning centers

“…Owing to these persistent efforts [17][18][19][20], some manufacturers have recently realized remarkable advances, and several conductors doped with APCs have become commercially available. However, there have been limited reports on the transport properties of these APC-doped conductors [7,[21][22][23], and very few comparative studies have focused on these conductors [24].…”