Effects of Wide Range Bending Strain on Critical Current of Bronze Route Nb3Sn Superconducting Strands.
Superconducting Niobium-Tin (Nb3Sn) plays important roles in magnet design for high
energy physics and fusion reactor applications. Nb3Sn is capable of carrying significant
amounts of current and producing strong magnetic fields, making it an ideal choice for
several components of the tokamak magnetic confinement system in the ITER experimental
fusion reactor. Despite its great ... read moresuperconducting properties, Nb3Sn demonstrates
degraded electrical properties when subjected to strain. After being cabled into a
Cable-in-Conduit Conductor, Nb3Sn wires are subjected to a complex strain state during
heat treatment and operation. The focus of this research was to examine a simpler
subunit of the system by isolating the effects of pure bending strain on the critical
current of a single Nb3Sn strand. Though there are several processes for manufacturing
Nb3Sn wires, the samples tested in this study were bronze route wires from European
Advanced Superconductors (EAS) and Hitachi Cable, Ltd. Pure bending experiments with
three distinct sample holders to cover a nominal bending range of 0.0-1.4% in a 4.2 K,
15 T environment at the National High Magnetic Field Laboratory were performed. Samples
from both manufacturers exhibited critical current degradation as high as 60%, but this
degradation was not permanent. Data analysis, additional test runs and finite element
analysis concluded that multiple strain cycles did not further degrade critical current
performance and that the sample holders accurately applied the desired strain to the
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Mechanical Engineering.
Advisor: Luisa Chiesa.
Committee: Gary Leisk, and Makoto Takayasu.
Keyword: Mechanical engineering.read less