Title :
Coupling Current and Hysteresis Losses of Bi2212 Round Wires With Twisted Filaments
Author :
Yifeng Yang ; Pelegrin, J. ; Young, E.A. ; Falorio, I. ; Ballarino, A. ; Bottura, L. ; Miao, H. ; Huang, Y.
Author_Institution :
Inst. of Cryogenics, Univ. of Southampton, Southampton, UK
Abstract :
AC loss measurements have been carried out on Bi2212 round wires of different twist pitches. With systematical variation of sample temperature (5 K-70 K) and ac field amplitude (≤ 0.2 T) as well as frequency (20 Hz-2 kHz) , this work shows (1) the full coupling of the non-twisted wire, (2) the uncoupling of sub-wires by twisting at moderate pitch up to 12 mm, (3) a relatively short time constant of milliseconds for the coupling current due to a high transverse resistivity, and (4) an effective (de)coupling diameter of 0.4 mm about 1.6 × of sub-wire bundles. The results suggest a promising potential for improving filament decoupling.
Keywords :
bismuth compounds; critical current density (superconductivity); electrical resistivity; flux pinning; high-temperature superconductors; magnetic hysteresis; magnetic leakage; multifilamentary superconductors; AC loss measurements; Bi2212 round wires; ac field amplitude; coupling current; effective decoupling diameter; filament decoupling; flux pinning induced magnetic hysteresis; frequency 20 Hz to 2 kHz; high-transverse resistivity; hysteresis losses; nontwisted wire; subwire bundles; subwire uncoupling; superconductor critical current; temperature 5 K to 70 K; twist pitches; twisted filaments; Couplings; Loss measurement; Magnetic field measurement; Superconducting filaments and wires; Superconducting magnets; Temperature; Wires; High Temperature Superconductors; High temperature superconductors; Superconducting Magnets,; superconducting magnets;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2014.2373655
