New Experiments Elucidating the Current Limiting Mechanisms of Ag-Sheathed (Bi,Pb)2Sr2Ca2Cu3Ox Tapes

Strain effects in high temperature superconductors investigated with magneto-optical imaging

“…These boundaries are mechanically weak and therefore most likely to break. Ultrasonic fracturing of filaments in a different study [11] gave the same average colonysize of 200 m.…”

The use of the in-field critical current density, Jc(0.1 T), as a better descriptor of (Bi, Pb)2Sr2Ca2Cu3Ox/Ag tape performance

“…6 In order to continue to increase J c it is necessary to understand and to minimize the effects of the multiple current-limiting mechanisms that operate in different field ranges for these tapes, for it is now understood that the mechanisms that limit J c in self-field may not be the same as those which limit J c in a magnetic field. 7 J c (0) primarily depends on the connectivity of the tape, and, in addition, it is becoming increasingly clear that self-fields can significantly suppress J c (0), especially in tapes with large critical currents. 8,9 In low fields, J c (H) is also controlled by the breaking of weak links by the magnetic field, which thereby reduces the effective cross section of the superconductor.…”

“…J c (H) is controlled by flux pinning, the strength of which can be characterized by the irreversibility field H*. Anderson et al have recently shown that there is no universal correlation between J c (0) and H*, 11 thus suggesting that J c (0) and H* can be optimized independently 7 and that a useful description of 2223 tape performance must include both parameters, J c (0) and H*. In this work, we show that more extensive electromagnetic characterizations of 2223 tapes can indeed yield additional vital information about their performance and current-limiting mechanisms.…”

Visualization of the grain structure in the filament cross sections of uniaxially textured high J c Bi-2223 tapes

“…© 2019 The Japan Society of Applied Physics Supplementary material for this article is available online T he (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x (Bi-2223) superconducting tape is the 1st generation high temperature superconductor (HTS) wire that has been extensively researched and developed as an industrial product over two decades. [1][2][3][4][5][6][7][8][9] During this period, several breakthroughs, in particular, the controlled overpressure sintering method (CT-OP) [10][11][12][13][14] and the lamination strengthen method [15][16][17][18] drastically raised the critical current density J c and tensile strength. Now the J c exceeds 5.5 × 10 4 A cm −2 at 77 K, self field, and the critical tensile stress where the J c starts dropping due to the mechanical fracture exceeds 500 MPa, expanding the opportunities of large projects such as the superconducting power cables [19][20][21] or the superconducting magnets for high field solenoids and 1 GHz nuclear magnetic resonance.…”