Characterization of Nb₃Sn superconducting strand under pure bending

Abstract

Characterizing the strain-dependent behavior of technological Nb₃Sn superconducting strand has been an important subject of research for the past 25 years. Most of the effort has focused on understanding the uniaxial tension and compression effects and applying this information to improve predictive scaling laws which are used for superconducting magnet design. However, the strain state of the strand in an actual magnet winding is often a complicated combination which includes uniaxial tension or compression, bending, and transverse compression. A bending mechanism was designed and used to characterize the bending strain behavior of two different types of Nb₃Sn superconducting strand at 4.2K in a magnetic field. Results showed that the critical current of the strand increased up to an applied bending strain between 0.2-0.3% and then decreased with continued applied strain.