Current–voltage characteristics of double disordered REBCO coated conductors exposed to magnetic fields with edge gradients. (12th September 2019)

• Record Type: Journal Article
• Authors: Gnilsen, Johannes; Usoskin, Alexander; Eisterer, Michael; Betz, Ulrich; Schlenga, Klaus
• Is Part Of: Superconductor science & technology. Volume 32:Number 10(2019:Oct.)
• Publication Date: 2019-09-12
• Subjects: high-temperature superconductors -- superconducting tapes -- yttrium compounds -- laser ablation -- epitaxial growth -- superconducting materials; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/1361-6668/ab3c09
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: 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.