High Compressive Axial Strain Effect on the Critical Current and Field of Nb3Sn Superconductor Wire
The axial strain dependence of the critical current Ic and effective upper critical field Bc2* have been measured on a series of Nb3Sn wire superconductors having initial compressive strain as large as -0.95% arising from thermal contraction of the conductor matrix. Results include data for binary Nb3Sn and ternary Nb3Sn with Ti additions. The effective upper critical field Bc2* is obtained using a general form of the pinning expression, since the data show that the Kramer method is not generally applicable to ternary Nb3Sn superconductors. The Ic and Bc2* data fit the strain scaling law well. The results are also consistent with earlier-published Tc vs. strain data for Nb3Sn at compressive strain as large as -0.85% and with Ic vs. strain data for stainless-steel reinforced Nb3Sn superconductors at compressive strain as large as -0.65%. The data contradict, however, recently reported Bc2* data obtained on multifilamentary Nb3Sn wires where high compressive strain was applied by soldering the wires to a bending beam and then flexing the beam.
KeywordsAxial Strain Compressive Strain Critical Current Critical Field Uniaxial Strain
Unable to display preview. Download preview PDF.
- 5.The dependence of Bc2* on strain for ternary (Nb-Ti)3Sn has been shown earlier to be steeper than for binary Nb3Sn. This is readily represented by the strain scaling law using a larger value of “a” in Eqn. 2.Google Scholar
- 7.M. Dunn, Dept. of Mech. Eng., Univ. of Colo., Boulder, CO, private communication.Google Scholar