Bi-2212 round wire development for high field applications

Reduced Magnetization and Loss in Ag–Mg Sheathed Bi2212 Wires: Systematics With Sample Twist Pitch and Length

“…In fact, the magnetization is linearly dependent upon sample length for the non-twisted set. When comparing twisted and non-twisted samples of similar length, the twisted sample has a greatly reduced d eff and loss compared to the non-twisted sample, consistent with the recent results of Miao et al [8].…”

“…1 (along with the results of the measurements on the non-twisted samples whose lengths most nearly match the lengths of the twisted samples). The magnetization of the twisted samples is clearly smaller than that of the non-twisted samples (for the same sample length), as we might generally expect, and as demonstrated recently in OST strands [8]. We also notice, however, that the magnetization of the non-twisted samples depends upon sample length.…”

“…Whereas twisting reduces eddy-current loss, it should also reduce the coupling due to bridging because, as the twist becomes tighter (i.e., as the twist pitch length decreases), the number of bridges within the twist pitch length decreases, reducing the amount of transverse current to below the total current which can flow down the length of the sample. Twisting has recently been applied to Bi2212 round wires [8], [9], and has indeed been shown to lead to a reduction in AC loss compared to non-twisted samples [8].…”

Comparison of growth texture in round Bi2212 and flat Bi2223 wires and its relation to high critical current density development

“…However, a major impediment to magnet applications of these HTS conductors is their 20-40:1 shape anisotropy, their large electromagnetic anisotropy and their delivery in fixed sizes determined by their complex manufacturing process, rather than by the desires of their users. On the other hand, Bi 2 Sr 2 CaCu 2 O x (Bi2212) is the only HTS cuprate in which high J c can be developed in a round wire form [13,14] which also allows it to be supplied in multiple multifilament architectures [15] and in the twisted state that benefits low hysteretic losses, isotropic properties and high magnetic field quality. Another huge advantage of round wires is that they can also be flexibly cabled into conductors of arbitrary current capacity, as is well demonstrated by many uses of Nb-Ti and Nb 3 Sn wires [16].…”

Statistical study of the void structure of Bi2212 multifilamentary superconducting wires and its effect on the critical current density

“…For practical Bi2212 multifilamentary wires with porous microstructure, usually, to improve the J c of wires, besides improving the number of Bi2212 filaments (can be implemented by means of increasing the number of filaments in bundles or/and the number of bundles), suppressing the void porosity of filaments is regarded as an effective method. So far, there have been many studies of making efforts on reducing the void porosity (for example, over-pressure processing) during heat treatment (Larbalestier et al, 2014;Jiang et al, 2011;Jiang et al, 2013;Naderi et al, 2013;Miao et al, 2014). Here, on the electrical model, for the wires with three practical conductor architectures, we predicted the porosity dependence of the J c of wires.…”