Indigenously developed bending strain setup for I-V characterization of superconducting tapes and wires

The indigenously developed bending strain setup to examine the effect of pure bending on critical current of superconducting tapes and strands has been presented in this paper. This set up is capable of applying various bending radius at cryogenic temperature with rack and pinion gear mechanism. The strain applied on samples can be controlled externally by torsional input which transferred in the form of bending radius during experiments. The working principle, design and optimization of this set up have been discussed. The performance and validation of set up has been done on various HTS tapes and copper strands at 77 K in actual experimental facility. The effect of bending radius (15.5 mm - 48 mm) i.e strain and ramp rate (2 amp/s - 8 amp/s) is observed on current capability of various HTS Tapes. The critical current capability of BSCCO tape without any strain is 133 A which is reduced to 93 A with 0.83% strain at ramp rate of 8 amp/s. The critical current capability of DI-BSCCO tape without any strain is 139.6 A which reduced to 97 A with 1% strain at ramp rate of 8 amp/s. The critical current capability of YBCO tape without any strain is 80 A which is reduced to 77.8 A with 1% strain at ramp rate of 8 amp/s. In mentioned conditions, it is observed that in uniform bending condition, the degradation in current carrying capacity BSCOO and DIBSCCO (∼30%) is more as compare to YBCO (∼2.75%) at 77K. The effect of pure mechanical strain has been experimentally observed and presented in this paper. (author)