Open AccessCurrent–voltage characteristics of double disordered REBCO coated conductors exposed to magnetic fields with edge gradients
Author(s) -
Johannes Gnilsen,
A. Usoskin,
M. Eisterer,
U. Betz,
K. Schlenga
Publication year - 2019
Publication title -
superconductor science and technology/superconductor science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.033
H-Index - 105
eISSN - 1361-6668
pISSN - 0953-2048
DOI - 10.1088/1361-6668/ab3c09
Subject(s) - materials science , magnet , electrical conductor , magnetic field , condensed matter physics , voltage , current (fluid) , field (mathematics) , enhanced data rates for gsm evolution , superconducting magnet , nuclear magnetic resonance , superconductivity , composite material , physics , thermodynamics , telecommunications , mathematics , quantum mechanics , computer science , pure mathematics
A study of HTS-coated tapes which are exposed to a low and medium field with a gradient in the flux density is performed in order to enable relevant and accurate tape characterization as well as to determine the relevant information for applications, where a magnetic field gradient occurs. In particular, the study is focused on ultra-high-magnet-field YBCO-coated tapes. Such tapes based on double disordered YBCO layer with intrinsic and extrinsic precipitations exhibit a ‘champion’ performance in ultra-high (31 T) magnetic fields. Alternative measurement techniques, based on miniature permanent magnets or a pulsed electro-magnet was developed to characterize the critical current, I c , in 0.5 and 3 T fields at 77 K, B // c , respectively. For the field dependence of the critical current, an ‘extended alpha approximation’ is suggested, which enables a sufficiently accurate description of the tape behavior in the low and medium field range, i.e. from 0 to 6 T. Local and integral voltage response in the tapes are analyzed and compared with experimental results. Observations of the effect that gains the influence of local I c -inhomogeneities exposed to a spatially confined magnetic field are described and discussed. The effects of local heating and cooling are shown to be limited via lowering the transport currents and finally a reduced power dissipation in the tape exposed to a localized magnetic field with two gradient zones was demonstrated. Correction factors needed to determine the critical current from the field dependence of the integral voltage response are derived and discussed.