Investigation of Different Angle Joining of Superconducting Tapes
Joining of superconducting wires and tapes is of significant importance for fabricating long conductors and for installation of superconductor devices. A technique for joining Ag-sheathed Bi-based superconducting single and multifilament tapes fabricated using a powder-in-tube technique has been developed. A number of joint configurations have been investigated for Ag-sheathed Bi-based superconducting single core and multifilament tapes. When the joining was performed at the final stage of the thermomechanical processes, the transport critical current (Ic) of the Ag-superconductor-superconductor-Ag (Ag-S-S-Ag) joining remains 60–80 % of Ic value of the normal region for single tapes with 0° joining. 45° joining for single core tapes can retain ∼20 % of the Ic of the normal region while 90° joining can hold less than 10% of the Ic of the normal region. The 0° joining for the multifilament holds 40 to 60% of current of the normal regions of the tapes. If the joining is carried out at the first stage of thermomechanical processes, the joint can retain nearly 100% of the Jc. This type of joining is useful to overcome the limitation of the powder-in-tube process. These results suggest that the critical current in the tapes is limited by high angle boundaries since the high angle joining results in a large proportion of high angle boundaries.
KeywordsHigh Angle Critical Current Critical Current Density Normal Region Thermomechanical Process
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